diff --git a/.circleci/config.yml b/.circleci/config.yml
index 3df8dd0af..67cfe19c3 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -3,7 +3,7 @@ version: 2
 defaults: &defaults
   working_directory: ~/repo
   docker:
-    - image: pyodide/pyodide-env:15
+    - image: pyodide/pyodide-env:16
   environment:
     - EMSDK_NUM_CORES: 3
       EMCC_CORES: 3
@@ -21,12 +21,8 @@ jobs:
           command: make lint
 
   test-docs:
-    working_directory: ~/repo
+    <<: *defaults
     resource_class: small
-
-    docker:
-      - image: cimg/python:3.8.2-node
-
     steps:
       - checkout
 
@@ -34,8 +30,6 @@ jobs:
           name: Install prerequisites
           command: |
             pip install -r docs/requirements-doc.txt
-            pip install pytest
-            sudo npm install -g jsdoc
 
       - run:
           name: Test docs
@@ -253,7 +247,7 @@ jobs:
     resource_class: small
 
     docker:
-      - image: cibuilds/github:0.13 
+      - image: cibuilds/github:0.13
 
     steps:
       - checkout
diff --git a/Dockerfile b/Dockerfile
index cb6e19c07..bf64934b7 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,3 +1,4 @@
+FROM node:14.16.1-buster-slim AS node-image
 FROM python:3.8.2-slim-buster
 
 RUN apt-get update \
@@ -6,7 +7,7 @@ RUN apt-get update \
                   bzip2 ccache clang-format-6.0 cmake f2c g++ gfortran git make \
                   patch pkg-config swig unzip wget xz-utils \
                   # testing packages: libgconf-2-4 is necessary for running chromium
-                  libgconf-2-4 "chromium=89.*" \
+                  libgconf-2-4 "chromium=90.*" \
   && rm -rf /var/lib/apt/lists/*
 
 RUN pip3 --no-cache-dir install \
@@ -23,7 +24,19 @@ RUN pip3 --no-cache-dir install \
   pytest-rerunfailures \
   pytest-xdist \
   pyyaml \
-  "selenium==4.0.0.b3"
+  "selenium==4.0.0.b3" \
+  # Docs requirements
+  sphinx                \
+  sphinx_book_theme     \
+  myst-parser==0.13.3    \
+  sphinxcontrib-napoleon  \
+  packaging               \
+  sphinx-js==3.1          \
+  autodocsumm             \
+  docutils==0.16          \
+  sphinx-argparse-cli~=1.6.0 \
+  sphinx-version-warning~=1.1.2 \
+  sphinx-issues
 
 # Get firefox 70.0.1 and geckodriver
 RUN wget -qO- https://ftp.mozilla.org/pub/firefox/releases/87.0/linux-x86_64/en-US/firefox-87.0.tar.bz2 | tar jx \
@@ -31,10 +44,22 @@ RUN wget -qO- https://ftp.mozilla.org/pub/firefox/releases/87.0/linux-x86_64/en-
   && wget -qO- https://github.com/mozilla/geckodriver/releases/download/v0.29.1/geckodriver-v0.29.1-linux64.tar.gz | tar zxC /usr/local/bin/
 
 # Get recent version of chromedriver
-RUN wget --quiet https://chromedriver.storage.googleapis.com/89.0.4389.23/chromedriver_linux64.zip \
+RUN wget --quiet https://chromedriver.storage.googleapis.com/90.0.4430.24/chromedriver_linux64.zip \
   && unzip chromedriver_linux64.zip \
   && mv $PWD/chromedriver /usr/local/bin \
   && rm -f chromedriver_linux64.zip
 
+COPY --from=node-image /usr/local/bin/node /usr/local/bin/
+COPY --from=node-image /usr/local/lib/node_modules /usr/local/lib/node_modules
+RUN ln -s ../lib/node_modules/npm/bin/npm-cli.js /usr/local/bin/npm \
+    && ln -s ../lib/node_modules/npm/bin/npx-cli.js /usr/local/bin/npx
+
+RUN npm install -g \
+  jsdoc \
+  uglify-js \
+  prettier \
+  rollup \
+  rollup-plugin-terser
+
 CMD ["/bin/sh"]
 WORKDIR /src
diff --git a/Makefile b/Makefile
index aecfe3fd6..8b3570cd5 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,8 @@ include Makefile.envs
 .PHONY=check
 
 FILEPACKAGER=$$EM_DIR/tools/file_packager.py
-UGLIFYJS=$(PYODIDE_ROOT)/node_modules/.bin/uglifyjs
+UGLIFYJS=npx uglifyjs
+PRETTIER=npx prettier
 
 CPYTHONROOT=cpython
 CPYTHONLIB=$(CPYTHONROOT)/installs/python-$(PYVERSION)/lib/python$(PYMINOR)
@@ -116,15 +117,14 @@ update_base_url: \
 test: all
 	pytest src emsdk/tests packages/*/test* pyodide_build -v
 
-
 lint:
 	# check for unused imports, the rest is done by black
 	flake8 --select=F401 src tools pyodide_build benchmark conftest.py docs
-	clang-format-6.0 -output-replacements-xml `find src -type f -regex ".*\.\(c\|h\|js\)"` | (! grep '<replacement ')
+	clang-format-6.0 -output-replacements-xml `find src -type f -regex ".*\.\(c\|h\\)"` | (! grep '<replacement ')
+	$(PRETTIER) --check `find src -type f -name '*.js'`
 	black --check .
 	mypy --ignore-missing-imports pyodide_build/ src/ packages/micropip/micropip/ packages/*/test* conftest.py docs
 
-
 apply-lint:
 	./tools/apply-lint.sh
 
@@ -149,7 +149,7 @@ clean-all: clean
 	$(CC) -o $@ -c $< $(MAIN_MODULE_CFLAGS) -Isrc/core/
 
 
-build/test.data: $(CPYTHONLIB) $(UGLIFYJS)
+build/test.data: $(CPYTHONLIB)
 	( \
 		cd $(CPYTHONLIB)/test; \
 		find . -type d -name __pycache__ -prune -exec rm -rf {} \; \
@@ -160,12 +160,6 @@ build/test.data: $(CPYTHONLIB) $(UGLIFYJS)
 	)
 	$(UGLIFYJS) build/test.js -o build/test.js
 
-
-$(UGLIFYJS): emsdk/emsdk/.complete
-	npm i --no-save uglify-js
-	touch -h $(UGLIFYJS)
-
-
 $(CPYTHONLIB): emsdk/emsdk/.complete $(PYODIDE_EMCC) $(PYODIDE_CXX)
 	date +"[%F %T] Building cpython..."
 	make -C $(CPYTHONROOT)
diff --git a/benchmark/benchmarks/lstsqr.py b/benchmark/benchmarks/lstsqr.py
index 0c5243fc1..2b21ab3dc 100644
--- a/benchmark/benchmarks/lstsqr.py
+++ b/benchmark/benchmarks/lstsqr.py
@@ -8,7 +8,7 @@ import numpy as np
 
 
 def lstsqr(x, y):
-    """ Computes the least-squares solution to a linear matrix equation. """
+    """Computes the least-squares solution to a linear matrix equation."""
     x_avg = np.average(x)
     y_avg = np.average(y)
     dx = x - x_avg
diff --git a/docs/sphinx_pyodide/sphinx_pyodide/jsdoc.py b/docs/sphinx_pyodide/sphinx_pyodide/jsdoc.py
index 3418b3fcc..9eac809ec 100644
--- a/docs/sphinx_pyodide/sphinx_pyodide/jsdoc.py
+++ b/docs/sphinx_pyodide/sphinx_pyodide/jsdoc.py
@@ -121,7 +121,7 @@ class PyodideAnalyzer:
 
 
 def get_jsdoc_content_directive(app):
-    """These directives need to close over app """
+    """These directives need to close over app"""
 
     class JsDocContent(Directive):
         """A directive that just dumps a summary table in place. There are no
diff --git a/run_docker b/run_docker
index 700f6c91a..0de7ce19e 100755
--- a/run_docker
+++ b/run_docker
@@ -1,5 +1,12 @@
 #!/usr/bin/env bash
 
+PYODIDE_IMAGE_REPO="pyodide"
+PYODIDE_IMAGE_TAG="16"
+PYODIDE_PREBUILT_IMAGE_TAG="0.17.0"
+DEFAULT_PYODIDE_DOCKER_IMAGE="${PYODIDE_IMAGE_REPO}/pyodide-env:${PYODIDE_IMAGE_TAG}"
+DEFAULT_PYODIDE_SYSTEM_PORT="8000"
+DOCKER_COMMAND="/bin/bash"
+
 set -eo pipefail
 
 
@@ -28,13 +35,6 @@ function error() {
   exit 255
 }
 
-
-PYODIDE_IMAGE_TAG="15"
-PYODIDE_PREBUILT_IMAGE_TAG="0.17.0"
-DEFAULT_PYODIDE_DOCKER_IMAGE="pyodide/pyodide-env:${PYODIDE_IMAGE_TAG}"
-DEFAULT_PYODIDE_SYSTEM_PORT="8000"
-DOCKER_COMMAND="/bin/bash"
-
 while [[ $# -gt 0 ]]
 do
   key="$1"
diff --git a/src/core/pyproxy.js b/src/core/pyproxy.js
index 66e1a5468..8557ebb4a 100644
--- a/src/core/pyproxy.js
+++ b/src/core/pyproxy.js
@@ -13,10 +13,9 @@
  * This file to be included from pyproxy.c This uses the JS_FILE macro defined
  * in include_js_file.h
  */
-// clang-format off
-JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
+JS_FILE(pyproxy_init_js, () => {
+  0, 0; /* Magic, see include_js_file.h */
   Module.PyProxies = {};
-  // clang-format on
 
   if (globalThis.FinalizationRegistry) {
     Module.finalizationRegistry = new FinalizationRegistry((ptr) => {
@@ -41,7 +40,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
     //   }
     // });
   } else {
-    Module.finalizationRegistry = {register() {}, unregister() {}};
+    Module.finalizationRegistry = { register() {}, unregister() {} };
     // Module.bufferFinalizationRegistry = finalizationRegistry;
   }
 
@@ -65,7 +64,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
    * still make "prototype in proxy" be true though.
    * @private
    */
-  Module.pyproxy_new = function(ptrobj) {
+  Module.pyproxy_new = function (ptrobj) {
     let flags = _pyproxy_getflags(ptrobj);
     let cls = Module.getPyProxyClass(flags);
     // Reflect.construct calls the constructor of Module.PyProxyClass but sets
@@ -87,8 +86,9 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
     } else {
       target = Object.create(cls.prototype);
     }
-    Object.defineProperty(target, "$$",
-                          {value : {ptr : ptrobj, type : 'PyProxy'}});
+    Object.defineProperty(target, "$$", {
+      value: { ptr: ptrobj, type: "PyProxy" },
+    });
     _Py_IncRef(ptrobj);
     let proxy = new Proxy(target, Module.PyProxyHandlers);
     Module.finalizationRegistry.register(proxy, ptrobj, proxy);
@@ -112,14 +112,13 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
    * PyProxy is minimal.
    * @private
    */
-  Module.getPyProxyClass = function(flags) {
+  Module.getPyProxyClass = function (flags) {
     let result = _pyproxyClassMap.get(flags);
     if (result) {
       return result;
     }
     let descriptors = {};
-    // clang-format off
-    for(let [feature_flag, methods] of [
+    for (let [feature_flag, methods] of [
       [HAS_LENGTH, Module.PyProxyLengthMethods],
       [HAS_GET, Module.PyProxyGetItemMethods],
       [HAS_SET, Module.PyProxySetItemMethods],
@@ -129,14 +128,13 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       [IS_AWAITABLE, Module.PyProxyAwaitableMethods],
       [IS_BUFFER, Module.PyProxyBufferMethods],
       [IS_CALLABLE, Module.PyProxyCallableMethods],
-    ]){
-      // clang-format on
+    ]) {
       if (flags & feature_flag) {
         Object.assign(descriptors, Object.getOwnPropertyDescriptors(methods));
       }
     }
     let new_proto = Object.create(Module.PyProxyClass.prototype, descriptors);
-    function PyProxy() {};
+    function PyProxy() {}
     PyProxy.prototype = new_proto;
     _pyproxyClassMap.set(flags, PyProxy);
     return PyProxy;
@@ -148,7 +146,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
   // Now a lot of boilerplate to wrap the abstract Object protocol wrappers
   // defined in pyproxy.c in Javascript functions.
 
-  Module.callPyObjectKwargs = function(ptrobj, ...jsargs) {
+  Module.callPyObjectKwargs = function (ptrobj, ...jsargs) {
     // We don't do any checking for kwargs, checks are in PyProxy.callKwargs
     // which only is used when the keyword arguments come from the user.
     let kwargs = jsargs.pop();
@@ -162,8 +160,13 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
     let idkwnames = Module.hiwire.new_value(kwargs_names);
     let idresult;
     try {
-      idresult =
-          __pyproxy_apply(ptrobj, idargs, num_pos_args, idkwnames, num_kwargs);
+      idresult = __pyproxy_apply(
+        ptrobj,
+        idargs,
+        num_pos_args,
+        idkwnames,
+        num_kwargs
+      );
     } catch (e) {
       Module.fatal_error(e);
     } finally {
@@ -176,16 +179,18 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
     return Module.hiwire.pop_value(idresult);
   };
 
-  // clang-format off
-  Module.callPyObject = function(ptrobj, ...jsargs) {
+  Module.callPyObject = function (ptrobj, ...jsargs) {
     return Module.callPyObjectKwargs(ptrobj, ...jsargs, {});
   };
-  // clang-format on
 
   Module.PyProxyClass = class {
-    constructor() { throw new TypeError('PyProxy is not a constructor'); }
+    constructor() {
+      throw new TypeError("PyProxy is not a constructor");
+    }
 
-    get[Symbol.toStringTag]() { return "PyProxy"; }
+    get [Symbol.toStringTag]() {
+      return "PyProxy";
+    }
     /**
      * The name of the type of the object.
      *
@@ -278,11 +283,14 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
     callKwargs(...jsargs) {
       if (jsargs.length === 0) {
         throw new TypeError(
-            "callKwargs requires at least one argument (the key word argument object)");
+          "callKwargs requires at least one argument (the key word argument object)"
+        );
       }
       let kwargs = jsargs[jsargs.length - 1];
-      if (kwargs.constructor !== undefined &&
-          kwargs.constructor.name !== "Object") {
+      if (
+        kwargs.constructor !== undefined &&
+        kwargs.constructor.name !== "Object"
+      ) {
         throw new TypeError("kwargs argument is not an object");
       }
       return Module.callPyObjectKwargs(_getPtr(this), ...jsargs);
@@ -309,7 +317,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
         _pythonexc2js();
       }
       return length;
-    }
+    },
   };
 
   // Controlled by HAS_GET, appears for any class with __getitem__,
@@ -323,7 +331,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * @param {any} key The key to look up.
      * @returns The corresponding value.
      */
-    get : function(key) {
+    get: function (key) {
       let ptrobj = _getPtr(this);
       let idkey = Module.hiwire.new_value(key);
       let idresult;
@@ -356,7 +364,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * @param {any} key The key to set.
      * @param {any} value The value to set it to.
      */
-    set : function(key, value) {
+    set: function (key, value) {
       let ptrobj = _getPtr(this);
       let idkey = Module.hiwire.new_value(key);
       let idval = Module.hiwire.new_value(value);
@@ -380,7 +388,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      *
      * @param {any} key The key to delete.
      */
-    delete : function(key) {
+    delete: function (key) {
       let ptrobj = _getPtr(this);
       let idkey = Module.hiwire.new_value(key);
       let errcode;
@@ -394,7 +402,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       if (errcode === -1) {
         _pythonexc2js();
       }
-    }
+    },
   };
 
   // Controlled by HAS_CONTAINS flag, appears for any class with __contains__ or
@@ -408,7 +416,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * @param {*} key The key to check for.
      * @returns {bool} Is ``key`` present?
      */
-    has : function(key) {
+    has: function (key) {
       let ptrobj = _getPtr(this);
       let idkey = Module.hiwire.new_value(key);
       let result;
@@ -426,7 +434,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
     },
   };
 
-  class TempError extends Error {};
+  class TempError extends Error {}
 
   /**
    * A helper for [Symbol.iterator].
@@ -485,7 +493,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      *
      * @returns {Iterator} An iterator for the proxied Python object.
      */
-    [Symbol.iterator] : function() {
+    [Symbol.iterator]: function () {
       let ptrobj = _getPtr(this);
       let token = {};
       let iterptr;
@@ -504,7 +512,9 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
   // Controlled by IS_ITERATOR, appears for any object with a __next__ or
   // tp_iternext method.
   Module.PyProxyIteratorMethods = {
-    [Symbol.iterator] : function() { return this; },
+    [Symbol.iterator]: function () {
+      return this;
+    },
     /**
      * This translates to the Python code ``next(obj)``. Returns the next value
      * of the generator. See the documentation for `Generator.prototype.next
@@ -524,7 +534,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * ``StopIteration(result_value)`` exception, ``next`` returns ``{done :
      * true, value : result_value}``.
      */
-    next : function(arg) {
+    next: function (arg) {
       let idresult;
       // Note: arg is optional, if arg is not supplied, it will be undefined
       // which gets converted to "Py_None". This is as intended.
@@ -545,7 +555,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
         _pythonexc2js();
       }
       let value = Module.hiwire.pop_value(idresult);
-      return {done, value};
+      return { done, value };
     },
   };
 
@@ -630,8 +640,10 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
   // here:
   // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
   Module.PyProxyHandlers = {
-    isExtensible : function() { return true },
-    has : function(jsobj, jskey) {
+    isExtensible: function () {
+      return true;
+    },
+    has: function (jsobj, jskey) {
       // Note: must report "prototype" in proxy when we are callable.
       // (We can return the wrong value from "get" handler though.)
       let objHasKey = Reflect.has(jsobj, jskey);
@@ -639,12 +651,12 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
         return true;
       }
       // python_hasattr will crash when given a Symbol.
-      if (typeof (jskey) === "symbol") {
+      if (typeof jskey === "symbol") {
         return false;
       }
       return python_hasattr(jsobj, jskey);
     },
-    get : function(jsobj, jskey) {
+    get: function (jsobj, jskey) {
       // Preference order:
       // 1. things we have to return to avoid making Javascript angry
       // 2. the result of Python getattr
@@ -653,11 +665,11 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       // 1. things we have to return to avoid making Javascript angry
       // This conditional looks funky but it's the only thing I found that
       // worked right in all cases.
-      if ((jskey in jsobj) && !(jskey in Object.getPrototypeOf(jsobj))) {
+      if (jskey in jsobj && !(jskey in Object.getPrototypeOf(jsobj))) {
         return Reflect.get(jsobj, jskey);
       }
       // python_getattr will crash when given a Symbol
-      if (typeof (jskey) === "symbol") {
+      if (typeof jskey === "symbol") {
         return Reflect.get(jsobj, jskey);
       }
       // 2. The result of getattr
@@ -668,13 +680,14 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       // 3. stuff from the prototype chain.
       return Reflect.get(jsobj, jskey);
     },
-    set : function(jsobj, jskey, jsval) {
+    set: function (jsobj, jskey, jsval) {
       // We're only willing to set properties on the python object, throw an
       // error if user tries to write over any key of type 1. things we have to
       // return to avoid making Javascript angry
-      if (typeof (jskey) === "symbol") {
+      if (typeof jskey === "symbol") {
         throw new TypeError(
-            `Cannot set read only field '${jskey.description}'`);
+          `Cannot set read only field '${jskey.description}'`
+        );
       }
       // Again this is a funny looking conditional, I found it as the result of
       // a lengthy search for something that worked right.
@@ -685,13 +698,14 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       python_setattr(jsobj, jskey, jsval);
       return true;
     },
-    deleteProperty : function(jsobj, jskey) {
+    deleteProperty: function (jsobj, jskey) {
       // We're only willing to delete properties on the python object, throw an
       // error if user tries to write over any key of type 1. things we have to
       // return to avoid making Javascript angry
-      if (typeof (jskey) === "symbol") {
+      if (typeof jskey === "symbol") {
         throw new TypeError(
-            `Cannot delete read only field '${jskey.description}'`);
+          `Cannot delete read only field '${jskey.description}'`
+        );
       }
       let descr = Object.getOwnPropertyDescriptor(jsobj, jskey);
       if (descr && !descr.writable) {
@@ -702,7 +716,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       // Otherwise Javascript will throw a TypeError.
       return !descr || descr.configurable;
     },
-    ownKeys : function(jsobj) {
+    ownKeys: function (jsobj) {
       let ptrobj = _getPtr(jsobj);
       let idresult;
       try {
@@ -717,11 +731,9 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       result.push(...Reflect.ownKeys(jsobj));
       return result;
     },
-    // clang-format off
-    apply : function(jsobj, jsthis, jsargs) {
+    apply: function (jsobj, jsthis, jsargs) {
       return jsobj.apply(jsthis, jsargs);
     },
-    // clang-format on
   };
 
   /**
@@ -735,7 +747,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * event loop if necessary.
      * @private
      */
-    _ensure_future : function() {
+    _ensure_future: function () {
       let ptrobj = _getPtr(this);
       let resolveHandle;
       let rejectHandle;
@@ -747,8 +759,11 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       let reject_handle_id = Module.hiwire.new_value(rejectHandle);
       let errcode;
       try {
-        errcode = __pyproxy_ensure_future(ptrobj, resolve_handle_id,
-                                          reject_handle_id);
+        errcode = __pyproxy_ensure_future(
+          ptrobj,
+          resolve_handle_id,
+          reject_handle_id
+        );
       } catch (e) {
         Module.fatal_error(e);
       } finally {
@@ -779,7 +794,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * argument if the awaitable fails.
      * @returns {Promise} The resulting Promise.
      */
-    then : function(onFulfilled, onRejected) {
+    then: function (onFulfilled, onRejected) {
       let promise = this._ensure_future();
       return promise.then(onFulfilled, onRejected);
     },
@@ -798,7 +813,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * argument if the awaitable fails.
      * @returns {Promise} The resulting Promise.
      */
-    catch : function(onRejected) {
+    catch: function (onRejected) {
       let promise = this._ensure_future();
       return promise.catch(onRejected);
     },
@@ -820,34 +835,32 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * result as the original Promise, but only after executing the
      * ``onFinally`` handler.
      */
-    finally : function(onFinally) {
+    finally: function (onFinally) {
       let promise = this._ensure_future();
       return promise.finally(onFinally);
-    }
+    },
   };
 
-  Module.PyProxyCallableMethods = {prototype : Function.prototype};
+  Module.PyProxyCallableMethods = { prototype: Function.prototype };
 
-  // clang-format off
   let type_to_array_map = new Map([
-    [ "i8", Int8Array ],
-    [ "u8", Uint8Array ],
-    [ "u8clamped", Uint8ClampedArray ],
-    [ "i16", Int16Array ],
-    [ "u16", Uint16Array ],
-    [ "i32", Int32Array ],
-    [ "u32", Uint32Array ],
-    [ "i32", Int32Array ],
-    [ "u32", Uint32Array ],
+    ["i8", Int8Array],
+    ["u8", Uint8Array],
+    ["u8clamped", Uint8ClampedArray],
+    ["i16", Int16Array],
+    ["u16", Uint16Array],
+    ["i32", Int32Array],
+    ["u32", Uint32Array],
+    ["i32", Int32Array],
+    ["u32", Uint32Array],
     // if these aren't available, will be globalThis.BigInt64Array will be
     // undefined rather than raising a ReferenceError.
-    [ "i64", globalThis.BigInt64Array],
-    [ "u64", globalThis.BigUint64Array],
-    [ "f32", Float32Array ],
-    [ "f64", Float64Array ],
-    [ "dataview", DataView ],
+    ["i64", globalThis.BigInt64Array],
+    ["u64", globalThis.BigUint64Array],
+    ["f32", Float32Array],
+    ["f64", Float64Array],
+    ["dataview", DataView],
   ]);
-  // clang-format on
 
   Module.PyProxyBufferMethods = {
     /**
@@ -880,7 +893,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
      * <https://docs.python.org/3/library/struct.html#format-strings>`_.
      * @returns :any:`PyBuffer`
      */
-    getBuffer : function(type) {
+    getBuffer: function (type) {
       let ArrayType = undefined;
       if (type) {
         ArrayType = type_to_array_map.get(type);
@@ -928,25 +941,32 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
         let bigEndian = false;
         if (ArrayType === undefined) {
           [ArrayType, bigEndian] = Module.processBufferFormatString(
-              format, " In this case, you can pass an explicit type argument.");
+            format,
+            " In this case, you can pass an explicit type argument."
+          );
         }
         let alignment =
-            parseInt(ArrayType.name.replace(/[^0-9]/g, "")) / 8 || 1;
+          parseInt(ArrayType.name.replace(/[^0-9]/g, "")) / 8 || 1;
         if (bigEndian && alignment > 1) {
           throw new Error(
-              "Javascript has no native support for big endian buffers. " +
+            "Javascript has no native support for big endian buffers. " +
               "In this case, you can pass an explicit type argument. " +
               "For instance, `getBuffer('dataview')` will return a `DataView`" +
               "which has native support for reading big endian data." +
               "Alternatively, toJs will automatically convert the buffer " +
-              "to little endian.");
+              "to little endian."
+          );
         }
         let numBytes = maxByteOffset - minByteOffset;
-        if (numBytes !== 0 && (startByteOffset % alignment !== 0 ||
-                               minByteOffset % alignment !== 0 ||
-                               maxByteOffset % alignment !== 0)) {
+        if (
+          numBytes !== 0 &&
+          (startByteOffset % alignment !== 0 ||
+            minByteOffset % alignment !== 0 ||
+            maxByteOffset % alignment !== 0)
+        ) {
           throw new Error(
-              `Buffer does not have valid alignment for a ${ArrayType.name}`);
+            `Buffer does not have valid alignment for a ${ArrayType.name}`
+          );
         }
         let numEntries = numBytes / alignment;
         let offset = (startByteOffset - minByteOffset) / alignment;
@@ -961,27 +981,26 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
         }
 
         success = true;
-        // clang-format off
-        let result = Object.create(Module.PyBuffer.prototype,
+        let result = Object.create(
+          Module.PyBuffer.prototype,
           Object.getOwnPropertyDescriptors({
             offset,
             readonly,
             format,
             itemsize,
-            ndim : shape.length,
-            nbytes : numBytes,
+            ndim: shape.length,
+            nbytes: numBytes,
             shape,
             strides,
             data,
             c_contiguous,
             f_contiguous,
-            _view_ptr : view_ptr,
-            _released : false
+            _view_ptr: view_ptr,
+            _released: false,
           })
         );
         // Module.bufferFinalizationRegistry.register(result, view_ptr, result);
         return result;
-        // clang-format on
       } finally {
         if (!success) {
           try {
@@ -992,10 +1011,9 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
           }
         }
       }
-    }
+    },
   };
 
-  // clang-format off
   /**
    * A class to allow access to a Python data buffers from Javascript. These are
    * produced by :any:`PyProxy.getBuffer` and cannot be constructed directly.
@@ -1062,7 +1080,6 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
    *            buffer.data.byteLength
    *        );
    */
-  // clang-format on
   Module.PyBuffer = class PyBuffer {
     constructor() {
       // FOR_JSDOC_ONLY is a macro that deletes its argument.
@@ -1151,7 +1168,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
          */
         this.f_contiguous;
       });
-      throw new TypeError('PyBuffer is not a constructor');
+      throw new TypeError("PyBuffer is not a constructor");
     }
 
     /**
@@ -1177,16 +1194,14 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
   // access like `pyodide.globals.x`.
   let globalsPropertyAccessWarned = false;
   let globalsPropertyAccessWarningMsg =
-      "Access to pyodide.globals via pyodide.globals.key is deprecated and " +
-      "will be removed in version 0.18.0. Use pyodide.globals.get('key'), " +
-      "pyodide.globals.set('key', value), pyodide.globals.delete('key') instead.";
+    "Access to pyodide.globals via pyodide.globals.key is deprecated and " +
+    "will be removed in version 0.18.0. Use pyodide.globals.get('key'), " +
+    "pyodide.globals.set('key', value), pyodide.globals.delete('key') instead.";
   let NamespaceProxyHandlers = {
-    // clang-format off
-    has : function(obj, key) {
+    has: function (obj, key) {
       return Reflect.has(obj, key) || obj.has(key);
     },
-    // clang-format on
-    get : function(obj, key) {
+    get: function (obj, key) {
       if (Reflect.has(obj, key)) {
         return Reflect.get(obj, key);
       }
@@ -1197,7 +1212,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       }
       return result;
     },
-    set : function(obj, key, value) {
+    set: function (obj, key, value) {
       if (Reflect.has(obj, key)) {
         throw new Error(`Cannot set read only field ${key}`);
       }
@@ -1207,7 +1222,7 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       }
       obj.set(key, value);
     },
-    ownKeys : function(obj) {
+    ownKeys: function (obj) {
       let result = new Set(Reflect.ownKeys(obj));
       let iter = obj.keys();
       for (let key of iter) {
@@ -1215,13 +1230,11 @@ JS_FILE(pyproxy_init_js, () => {0,0; /* Magic, see include_js_file.h */
       }
       iter.destroy();
       return Array.from(result);
-    }
+    },
   };
 
-  // clang-format off
   Module.wrapNamespace = function wrapNamespace(ns) {
     return new Proxy(ns, NamespaceProxyHandlers);
   };
-  // clang-format on
   return 0;
 });
diff --git a/src/core/python2js_buffer.js b/src/core/python2js_buffer.js
index 38d1ae541..9e4c1869e 100644
--- a/src/core/python2js_buffer.js
+++ b/src/core/python2js_buffer.js
@@ -17,89 +17,92 @@ JS_FILE(python2js_buffer_init, () => {
    *      is true if the format suggests a big endian array.
    * @private
    */
-  Module.processBufferFormatString = function(formatStr, errorMessage = "") {
+  Module.processBufferFormatString = function (formatStr, errorMessage = "") {
     if (formatStr.length > 2) {
-      throw new Error("Expected format string to have length <= 2, " +
-                      `got '${formatStr}'.` + errorMessage);
+      throw new Error(
+        "Expected format string to have length <= 2, " +
+          `got '${formatStr}'.` +
+          errorMessage
+      );
     }
     let formatChar = formatStr.slice(-1);
     let alignChar = formatStr.slice(0, -1);
     let bigEndian;
     switch (alignChar) {
-    case "!":
-    case ">":
-      bigEndian = true;
-      break;
-    case "<":
-    case "@":
-    case "=":
-    case "":
-      bigEndian = false;
-      break;
-    default:
-      throw new Error(`Unrecognized alignment character ${alignChar}.` +
-                      errorMessage);
+      case "!":
+      case ">":
+        bigEndian = true;
+        break;
+      case "<":
+      case "@":
+      case "=":
+      case "":
+        bigEndian = false;
+        break;
+      default:
+        throw new Error(
+          `Unrecognized alignment character ${alignChar}.` + errorMessage
+        );
     }
     let arrayType;
     switch (formatChar) {
-    case 'b':
-      arrayType = Int8Array;
-      break;
-    case 's':
-    case 'p':
-    case 'c':
-    case 'B':
-    case '?':
-      arrayType = Uint8Array;
-      break;
-    case 'h':
-      arrayType = Int16Array;
-      break;
-    case 'H':
-      arrayType = Uint16Array;
-      break;
-    case 'i':
-    case 'l':
-    case 'n':
-      arrayType = Int32Array;
-      break;
-    case 'I':
-    case 'L':
-    case 'N':
-    case 'P':
-      arrayType = Uint32Array;
-      break;
-    case 'q':
-      // clang-format off
-            if (globalThis.BigInt64Array === undefined) {
-        // clang-format on
-        throw new Error("BigInt64Array is not supported on this browser." +
-                        errorMessage);
-      }
-      arrayType = BigInt64Array;
-      break;
-    case 'Q':
-      // clang-format off
-            if (globalThis.BigUint64Array === undefined) {
-        // clang-format on
-        throw new Error("BigUint64Array is not supported on this browser." +
-                        errorMessage);
-      }
-      arrayType = BigUint64Array;
-      break;
-    case 'f':
-      arrayType = Float32Array;
-      break;
-    case 'd':
-      arrayType = Float64Array;
-      break;
-    case "e":
-      throw new Error("Javascript has no Float16 support.");
-    default:
-      throw new Error(`Unrecognized format character '${formatChar}'.` +
-                      errorMessage);
+      case "b":
+        arrayType = Int8Array;
+        break;
+      case "s":
+      case "p":
+      case "c":
+      case "B":
+      case "?":
+        arrayType = Uint8Array;
+        break;
+      case "h":
+        arrayType = Int16Array;
+        break;
+      case "H":
+        arrayType = Uint16Array;
+        break;
+      case "i":
+      case "l":
+      case "n":
+        arrayType = Int32Array;
+        break;
+      case "I":
+      case "L":
+      case "N":
+      case "P":
+        arrayType = Uint32Array;
+        break;
+      case "q":
+        if (globalThis.BigInt64Array === undefined) {
+          throw new Error(
+            "BigInt64Array is not supported on this browser." + errorMessage
+          );
+        }
+        arrayType = BigInt64Array;
+        break;
+      case "Q":
+        if (globalThis.BigUint64Array === undefined) {
+          throw new Error(
+            "BigUint64Array is not supported on this browser." + errorMessage
+          );
+        }
+        arrayType = BigUint64Array;
+        break;
+      case "f":
+        arrayType = Float32Array;
+        break;
+      case "d":
+        arrayType = Float64Array;
+        break;
+      case "e":
+        throw new Error("Javascript has no Float16 support.");
+      default:
+        throw new Error(
+          `Unrecognized format character '${formatChar}'.` + errorMessage
+        );
     }
-    return [ arrayType, bigEndian ];
+    return [arrayType, bigEndian];
   };
 
   /**
@@ -113,7 +116,7 @@ JS_FILE(python2js_buffer_init, () => {
    *  the WASM heap)
    * @private
    */
-  Module.python2js_buffer_1d_contiguous = function(ptr, stride, n) {
+  Module.python2js_buffer_1d_contiguous = function (ptr, stride, n) {
     "use strict";
     let byteLength = stride * n;
     // Note: slice here is a copy (as opposed to subarray which is not)
@@ -135,8 +138,13 @@ JS_FILE(python2js_buffer_init, () => {
    *  the WASM heap)
    * @private
    */
-  Module.python2js_buffer_1d_noncontiguous = function(ptr, stride, suboffset, n,
-                                                      itemsize) {
+  Module.python2js_buffer_1d_noncontiguous = function (
+    ptr,
+    stride,
+    suboffset,
+    n,
+    itemsize
+  ) {
     "use strict";
     let byteLength = itemsize * n;
     // Make new memory of the appropriate size
@@ -171,13 +179,12 @@ JS_FILE(python2js_buffer_init, () => {
    * @returns A nested Javascript array, the result of the conversion.
    * @private
    */
-  Module._python2js_buffer_recursive = function(ptr, curdim, bufferData) {
+  Module._python2js_buffer_recursive = function (ptr, curdim, bufferData) {
     "use strict";
     // When indexing HEAP32 we need to divide the pointer by 4
     let n = HEAP32[bufferData.shape / 4 + curdim];
     let stride = HEAP32[bufferData.strides / 4 + curdim];
     let suboffset = -1;
-    // clang-format off
     if (bufferData.suboffsets !== 0) {
       suboffset = HEAP32[bufferData.suboffsets / 4 + curdim];
     }
@@ -188,11 +195,15 @@ JS_FILE(python2js_buffer_init, () => {
         arraybuffer = Module.python2js_buffer_1d_contiguous(ptr, stride, n);
       } else {
         arraybuffer = Module.python2js_buffer_1d_noncontiguous(
-            ptr, stride, suboffset, n, bufferData.itemsize);
+          ptr,
+          stride,
+          suboffset,
+          n,
+          bufferData.itemsize
+        );
       }
       return bufferData.converter(arraybuffer);
     }
-    // clang-format on
 
     let result = [];
     for (let i = 0; i < n; ++i) {
@@ -203,7 +214,8 @@ JS_FILE(python2js_buffer_init, () => {
         curptr = HEAP32[curptr / 4] + suboffset;
       }
       result.push(
-          Module._python2js_buffer_recursive(curPtr, curdim + 1, bufferData));
+        Module._python2js_buffer_recursive(curPtr, curdim + 1, bufferData)
+      );
     }
     return result;
   };
@@ -224,45 +236,39 @@ JS_FILE(python2js_buffer_init, () => {
    * conversion.
    * @returns A converter function ArrayBuffer => TypedArray
    */
-  Module.get_converter = function(format, itemsize) {
+  Module.get_converter = function (format, itemsize) {
     "use strict";
     let formatStr = UTF8ToString(format);
     let [ArrayType, bigEndian] = Module.processBufferFormatString(formatStr);
     let formatChar = formatStr.slice(-1);
-    // clang-format off
     switch (formatChar) {
       case "s":
         let decoder = new TextDecoder("utf8");
         return (buff) => decoder.decode(buff);
       case "?":
-        return (buff) => Array.from(new Uint8Array(buff), x => !!x);
+        return (buff) => Array.from(new Uint8Array(buff), (x) => !!x);
     }
-    // clang-format on
 
     if (!bigEndian) {
-      // clang-format off
-      return buff => new ArrayType(buff);
-      // clang-format on
+      return (buff) => new ArrayType(buff);
     }
     let getFuncName;
     let setFuncName;
     switch (itemsize) {
-    case 2:
-      getFuncName = "getUint16";
-      setFuncName = "setUint16";
-      break;
-    case 4:
-      getFuncName = "getUint32";
-      setFuncName = "setUint32";
-      break;
-    case 8:
-      getFuncName = "getFloat64";
-      setFuncName = "setFloat64";
-      break;
-    default:
-      // clang-format off
-        throw new Error(`Unexpected size ${ itemsize }`);
-      // clang-format on
+      case 2:
+        getFuncName = "getUint16";
+        setFuncName = "setUint16";
+        break;
+      case 4:
+        getFuncName = "getUint32";
+        setFuncName = "setUint32";
+        break;
+      case 8:
+        getFuncName = "getFloat64";
+        setFuncName = "setFloat64";
+        break;
+      default:
+        throw new Error(`Unexpected size ${itemsize}`);
     }
     function swapFunc(buff) {
       let dataview = new DataView(buff);
@@ -274,8 +280,6 @@ JS_FILE(python2js_buffer_init, () => {
       }
       return buff;
     }
-    // clang-format off
-    return buff => new ArrayType(swapFunc(buff));
-    // clang-format on
+    return (buff) => new ArrayType(swapFunc(buff));
   };
 });
diff --git a/src/pyodide-py/_pyodide/_core.py b/src/pyodide-py/_pyodide/_core.py
index f32f38d47..6f8a67650 100644
--- a/src/pyodide-py/_pyodide/_core.py
+++ b/src/pyodide-py/_pyodide/_core.py
@@ -30,7 +30,7 @@ try:
         """
 
         def __init__(self):
-            """"""
+            """ """
 
         def object_entries(self) -> "JsProxy":
             "The Javascript API ``Object.entries(object)``"
diff --git a/src/pyodide-py/pyodide/console.py b/src/pyodide-py/pyodide/console.py
index cf3ccefbe..5fbd2407c 100644
--- a/src/pyodide-py/pyodide/console.py
+++ b/src/pyodide-py/pyodide/console.py
@@ -136,7 +136,7 @@ class _InteractiveConsole(code.InteractiveConsole):
         self.compile.compiler.flags |= ast.PyCF_ALLOW_TOP_LEVEL_AWAIT  # type: ignore
 
     def redirect_stdstreams(self):
-        """ Toggle stdout/stderr redirections. """
+        """Toggle stdout/stderr redirections."""
         # already redirected?
         if self._streams_redirected:
             return
@@ -193,7 +193,7 @@ class _InteractiveConsole(code.InteractiveConsole):
             self.restore_stdstreams()
 
     def flush_all(self):
-        """ Force stdout/stderr flush. """
+        """Force stdout/stderr flush."""
         with self.stdstreams_redirections():
             sys.stdout.flush()
             sys.stderr.flush()
@@ -264,7 +264,7 @@ class _InteractiveConsole(code.InteractiveConsole):
         self.restore_stdstreams()
 
     def banner(self):
-        """ A banner similar to the one printed by the real Python interpreter. """
+        """A banner similar to the one printed by the real Python interpreter."""
         # copyied from https://github.com/python/cpython/blob/799f8489d418b7f9207d333eac38214931bd7dcc/Lib/code.py#L214
         cprt = 'Type "help", "copyright", "credits" or "license" for more information.'
         version = platform.python_version()
diff --git a/src/pyodide.js b/src/pyodide.js
index a7b071eb9..88fe1c3c6 100644
--- a/src/pyodide.js
+++ b/src/pyodide.js
@@ -20,11 +20,12 @@ globalThis.pyodide = {};
  * @returns The Pyodide module.
  * @async
  */
-globalThis.loadPyodide = async function(config = {}) {
+globalThis.loadPyodide = async function (config = {}) {
   if (globalThis.__pyodideLoading) {
     if (globalThis.languagePluginURL) {
       throw new Error(
-          "Pyodide is already loading because languagePluginURL is defined.");
+        "Pyodide is already loading because languagePluginURL is defined."
+      );
     } else {
       throw new Error("Pyodide is already loading.");
     }
@@ -36,10 +37,10 @@ globalThis.loadPyodide = async function(config = {}) {
   // indexURL in any case.
   let baseURL = config.indexURL || "{{ PYODIDE_BASE_URL }}";
   if (baseURL.endsWith(".js")) {
-    baseURL = baseURL.substr(0, baseURL.lastIndexOf('/'));
+    baseURL = baseURL.substr(0, baseURL.lastIndexOf("/"));
   }
   if (!baseURL.endsWith("/")) {
-    baseURL += '/';
+    baseURL += "/";
   }
 
   ////////////////////////////////////////////////////////////
@@ -54,21 +55,28 @@ globalThis.loadPyodide = async function(config = {}) {
     if (match) {
       return match[1];
     }
-  };
+  }
 
   let loadScript;
-  if (self.document) { // browser
+  if (self.document) {
+    // browser
     loadScript = (url) => import(url);
-  } else if (self.importScripts) { // webworker
-    loadScript = async (url) => {  // This is async only for consistency
+  } else if (self.importScripts) {
+    // webworker
+    loadScript = async (url) => {
+      // This is async only for consistency
       self.importScripts(url);
     };
   } else {
     throw new Error("Cannot determine runtime environment");
   }
 
-  function recursiveDependencies(names, _messageCallback, errorCallback,
-                                 sharedLibsOnly) {
+  function recursiveDependencies(
+    names,
+    _messageCallback,
+    errorCallback,
+    sharedLibsOnly
+  ) {
     const packages = Module.packages.dependencies;
     const loadedPackages = Module.loadedPackages;
     const sharedLibraries = Module.packages.shared_library;
@@ -93,8 +101,11 @@ globalThis.loadPyodide = async function(config = {}) {
       const pkgname = _uri_to_package_name(name);
       if (pkgname !== undefined) {
         if (toLoad.has(pkgname) && toLoad.get(pkgname) !== name) {
-          errorCallback(`Loading same package ${pkgname} from ${name} and ${
-              toLoad.get(pkgname)}`);
+          errorCallback(
+            `Loading same package ${pkgname} from ${name} and ${toLoad.get(
+              pkgname
+            )}`
+          );
           continue;
         }
         toLoad.set(pkgname, name);
@@ -129,15 +140,15 @@ globalThis.loadPyodide = async function(config = {}) {
         let package_uri = toLoad.get(pkg);
         if (package_uri != DEFAULT_CHANNEL) {
           return package_uri.replace(/\.js$/, ".data");
-        };
-      };
+        }
+      }
       return baseURL + path;
     };
 
     if (toLoad.size === 0) {
-      return Promise.resolve('No new packages to load');
+      return Promise.resolve("No new packages to load");
     } else {
-      let packageNames = Array.from(toLoad.keys()).join(', ');
+      let packageNames = Array.from(toLoad.keys()).join(", ");
       messageCallback(`Loading ${packageNames}`);
     }
 
@@ -155,19 +166,21 @@ globalThis.loadPyodide = async function(config = {}) {
           continue;
         } else {
           errorCallback(
-              `URI mismatch, attempting to load package ${pkg} from ${uri} ` +
-              `while it is already loaded from ${
-                  loaded}. To override a dependency, ` +
-              `load the custom package first.`);
+            `URI mismatch, attempting to load package ${pkg} from ${uri} ` +
+              `while it is already loaded from ${loaded}. To override a dependency, ` +
+              `load the custom package first.`
+          );
           continue;
         }
       }
       let scriptSrc = uri === DEFAULT_CHANNEL ? `${baseURL}${pkg}.js` : uri;
       messageCallback(`Loading ${pkg} from ${scriptSrc}`);
-      scriptPromises.push(loadScript(scriptSrc).catch(() => {
-        errorCallback(`Couldn't load package from URL ${scriptSrc}`);
-        toLoad.delete(pkg);
-      }));
+      scriptPromises.push(
+        loadScript(scriptSrc).catch(() => {
+          errorCallback(`Couldn't load package from URL ${scriptSrc}`);
+          toLoad.delete(pkg);
+        })
+      );
     }
 
     // When the JS loads, it synchronously adds a runDependency to emscripten.
@@ -175,7 +188,7 @@ globalThis.loadPyodide = async function(config = {}) {
     // emscripten. This function returns a promise that resolves when there are
     // no pending runDependencies.
     function waitRunDependency() {
-      const promise = new Promise(r => {
+      const promise = new Promise((r) => {
         Module.monitorRunDependencies = (n) => {
           if (n === 0) {
             r();
@@ -207,10 +220,10 @@ globalThis.loadPyodide = async function(config = {}) {
 
     let resolveMsg;
     if (packageList.length > 0) {
-      let packageNames = packageList.join(', ');
+      let packageNames = packageList.join(", ");
       resolveMsg = `Loaded ${packageNames}`;
     } else {
-      resolveMsg = 'No packages loaded';
+      resolveMsg = "No packages loaded";
     }
 
     Module.reportUndefinedSymbols();
@@ -219,9 +232,10 @@ globalThis.loadPyodide = async function(config = {}) {
 
     // We have to invalidate Python's import caches, or it won't
     // see the new files.
-    Module.runPythonSimple('import importlib\n' +
-                           'importlib.invalidate_caches()\n');
-  };
+    Module.runPythonSimple(
+      "import importlib\n" + "importlib.invalidate_caches()\n"
+    );
+  }
 
   // This is a promise that is resolved iff there are no pending package loads.
   // It never fails.
@@ -235,7 +249,7 @@ globalThis.loadPyodide = async function(config = {}) {
   async function acquirePackageLock() {
     let old_lock = _package_lock;
     let releaseLock;
-    _package_lock = new Promise(resolve => releaseLock = resolve);
+    _package_lock = new Promise((resolve) => (releaseLock = resolve));
     await old_lock;
     return releaseLock;
   }
@@ -268,7 +282,7 @@ globalThis.loadPyodide = async function(config = {}) {
    *    messages (optional)
    * @async
    */
-  Module.loadPackage = async function(names, messageCallback, errorCallback) {
+  Module.loadPackage = async function (names, messageCallback, errorCallback) {
     if (Module.isPyProxy(names)) {
       let temp;
       try {
@@ -280,14 +294,18 @@ globalThis.loadPyodide = async function(config = {}) {
     }
 
     if (!Array.isArray(names)) {
-      names = [ names ];
+      names = [names];
     }
     // get shared library packages and load those first
     // otherwise bad things happen with linking them in firefox.
     let sharedLibraryNames = [];
     try {
-      let sharedLibraryPackagesToLoad =
-          recursiveDependencies(names, messageCallback, errorCallback, true);
+      let sharedLibraryPackagesToLoad = recursiveDependencies(
+        names,
+        messageCallback,
+        errorCallback,
+        true
+      );
       for (let pkg of sharedLibraryPackagesToLoad) {
         sharedLibraryNames.push(pkg[0]);
       }
@@ -310,20 +328,23 @@ globalThis.loadPyodide = async function(config = {}) {
       }
     }
     let dynamicLoadHandler = {
-      get : function(obj, prop) {
-        if (prop === 'handle') {
-          return function(bytes, name) {
+      get: function (obj, prop) {
+        if (prop === "handle") {
+          return function (bytes, name) {
             obj[prop].apply(obj, arguments);
-            this["asyncWasmLoadPromise"] =
-                this["asyncWasmLoadPromise"].then(function() {
-                  Module.loadDynamicLibrary(name,
-                                            {global : true, nodelete : true})
+            this["asyncWasmLoadPromise"] = this["asyncWasmLoadPromise"].then(
+              function () {
+                Module.loadDynamicLibrary(name, {
+                  global: true,
+                  nodelete: true,
                 });
-          }
+              }
+            );
+          };
         } else {
           return obj[prop];
         }
-      }
+      },
     };
     var loadPluginOverride = new Proxy(oldPlugin, dynamicLoadHandler);
     // restore the preload plugin
@@ -331,11 +352,17 @@ globalThis.loadPyodide = async function(config = {}) {
 
     let releaseLock = await acquirePackageLock();
     try {
-      await _loadPackage(sharedLibraryNames, messageCallback || console.log,
-                         errorCallback || console.error);
+      await _loadPackage(
+        sharedLibraryNames,
+        messageCallback || console.log,
+        errorCallback || console.error
+      );
       Module.preloadPlugins.shift(loadPluginOverride);
-      await _loadPackage(names, messageCallback || console.log,
-                         errorCallback || console.error);
+      await _loadPackage(
+        names,
+        messageCallback || console.log,
+        errorCallback || console.error
+      );
     } finally {
       releaseLock();
     }
@@ -357,42 +384,39 @@ globalThis.loadPyodide = async function(config = {}) {
     }
     try {
       recurse();
-    } catch (err) {
-      ;
-    }
+    } catch (err) {}
 
     let recursionLimit = depth / 50;
     if (recursionLimit > 1000) {
       recursionLimit = 1000;
     }
     pyodide.runPythonSimple(
-        `import sys; sys.setrecursionlimit(int(${recursionLimit}))`);
-  };
+      `import sys; sys.setrecursionlimit(int(${recursionLimit}))`
+    );
+  }
 
   ////////////////////////////////////////////////////////////
   // Rearrange namespace for public API
-  // clang-format off
   let PUBLIC_API = [
-    'globals',
-    'pyodide_py',
-    'version',
-    'loadPackage',
-    'loadPackagesFromImports',
-    'loadedPackages',
-    'isPyProxy',
-    'pyimport',
-    'runPython',
-    'runPythonAsync',
-    'registerJsModule',
-    'unregisterJsModule',
-    'setInterruptBuffer',
-    'toPy',
-    'PythonError',
+    "globals",
+    "pyodide_py",
+    "version",
+    "loadPackage",
+    "loadPackagesFromImports",
+    "loadedPackages",
+    "isPyProxy",
+    "pyimport",
+    "runPython",
+    "runPythonAsync",
+    "registerJsModule",
+    "unregisterJsModule",
+    "setInterruptBuffer",
+    "toPy",
+    "PythonError",
   ];
-  // clang-format on
 
   function makePublicAPI(module, public_api) {
-    let namespace = {_module : module};
+    let namespace = { _module: module };
     module.public_api = namespace;
     for (let name of public_api) {
       namespace[name] = module[name];
@@ -405,37 +429,41 @@ globalThis.loadPyodide = async function(config = {}) {
 
   Module.noImageDecoding = true;
   Module.noAudioDecoding = true;
-  Module.noWasmDecoding =
-      false; // we preload wasm using the built in plugin now
+  Module.noWasmDecoding = false; // we preload wasm using the built in plugin now
   Module.preloadedWasm = {};
 
   let fatal_error_occurred = false;
-  Module.fatal_error = function(e) {
+  Module.fatal_error = function (e) {
     if (fatal_error_occurred) {
       console.error("Recursive call to fatal_error. Inner error was:");
       console.error(e);
       return;
     }
     fatal_error_occurred = true;
-    console.error("Pyodide has suffered a fatal error. " +
-                  "Please report this to the Pyodide maintainers.");
-    console.error("The cause of the fatal error was:")
+    console.error(
+      "Pyodide has suffered a fatal error. " +
+        "Please report this to the Pyodide maintainers."
+    );
+    console.error("The cause of the fatal error was:");
     console.error(e);
     try {
       let fd_stdout = 1;
-      Module.__Py_DumpTraceback(fd_stdout,
-                                Module._PyGILState_GetThisThreadState());
+      Module.__Py_DumpTraceback(
+        fd_stdout,
+        Module._PyGILState_GetThisThreadState()
+      );
       for (let key of PUBLIC_API) {
         if (key === "version") {
           continue;
         }
         Object.defineProperty(Module.public_api, key, {
-          enumerable : true,
-          configurable : true,
-          get : () => {
+          enumerable: true,
+          configurable: true,
+          get: () => {
             throw new Error(
-                "Pyodide already fatally failed and can no longer be used.");
-          }
+              "Pyodide already fatally failed and can no longer be used."
+            );
+          },
         });
       }
       if (Module.on_fatal) {
@@ -469,7 +497,6 @@ globalThis.loadPyodide = async function(config = {}) {
    */
   Module.globals = {}; // actually defined in runPythonSimple below
 
-  // clang-format off
   /**
    * A Javascript error caused by a Python exception.
    *
@@ -494,7 +521,7 @@ globalThis.loadPyodide = async function(config = {}) {
   Module.PythonError = class PythonError {
     // actually defined in error_handling.c. TODO: would be good to move this
     // documentation and the definition of PythonError to error_handling.js
-    constructor(){
+    constructor() {
       /**
        * The Python traceback.
        * @type {string}
@@ -502,7 +529,6 @@ globalThis.loadPyodide = async function(config = {}) {
       this.message;
     }
   };
-  // clang-format on
 
   /**
    *
@@ -539,7 +565,7 @@ globalThis.loadPyodide = async function(config = {}) {
    *
    * @private
    */
-  Module.runPythonSimple = function(code) {
+  Module.runPythonSimple = function (code) {
     let code_c_string = Module.stringToNewUTF8(code);
     let errcode;
     try {
@@ -567,11 +593,10 @@ globalThis.loadPyodide = async function(config = {}) {
    * @returns The result of the Python code translated to Javascript. See the
    *          documentation for :any:`pyodide.eval_code` for more info.
    */
-  Module.runPython = function(code, globals = Module.globals) {
+  Module.runPython = function (code, globals = Module.globals) {
     return Module.pyodide_py.eval_code(code, globals);
   };
 
-  // clang-format off
   /**
    * Inspect a Python code chunk and use :js:func:`pyodide.loadPackage` to
    * install any known packages that the code chunk imports. Uses the Python API
@@ -593,7 +618,11 @@ globalThis.loadPyodide = async function(config = {}) {
    * :any:`pyodide.loadPackage` (optional).
    * @async
    */
-  Module.loadPackagesFromImports = async function(code, messageCallback, errorCallback) {
+  Module.loadPackagesFromImports = async function (
+    code,
+    messageCallback,
+    errorCallback
+  ) {
     let imports = Module.pyodide_py.find_imports(code).toJs();
     if (imports.length === 0) {
       return;
@@ -607,11 +636,12 @@ globalThis.loadPyodide = async function(config = {}) {
     }
     if (packages.size) {
       await Module.loadPackage(
-        Array.from(packages.keys()), messageCallback, errorCallback
+        Array.from(packages.keys()),
+        messageCallback,
+        errorCallback
       );
     }
   };
-  // clang-format on
 
   /**
    * Access a Python object in the global namespace from Javascript.
@@ -622,10 +652,11 @@ globalThis.loadPyodide = async function(config = {}) {
    * @param {string} name Python variable name
    * @returns The Python object translated to Javascript.
    */
-  Module.pyimport = name => {
+  Module.pyimport = (name) => {
     console.warn(
-        "Access to the Python global namespace via pyodide.pyimport is deprecated and " +
-        "will be removed in version 0.18.0. Use pyodide.globals.get('key') instead.");
+      "Access to the Python global namespace via pyodide.pyimport is deprecated and " +
+        "will be removed in version 0.18.0. Use pyodide.globals.get('key') instead."
+    );
     return Module.globals.get(name);
   };
   /**
@@ -649,7 +680,7 @@ globalThis.loadPyodide = async function(config = {}) {
    * @returns The result of the Python code translated to Javascript.
    * @async
    */
-  Module.runPythonAsync = async function(code) {
+  Module.runPythonAsync = async function (code) {
     let coroutine = Module.pyodide_py.eval_code_async(code, Module.globals);
     try {
       let result = await coroutine;
@@ -659,7 +690,6 @@ globalThis.loadPyodide = async function(config = {}) {
     }
   };
 
-  // clang-format off
   /**
    * Registers the Javascript object ``module`` as a Javascript module named
    * ``name``. This module can then be imported from Python using the standard
@@ -671,7 +701,7 @@ globalThis.loadPyodide = async function(config = {}) {
    * @param {string} name Name of the Javascript module to add
    * @param {object} module Javascript object backing the module
    */
-  Module.registerJsModule = function(name, module) {
+  Module.registerJsModule = function (name, module) {
     Module.pyodide_py.register_js_module(name, module);
   };
 
@@ -686,10 +716,9 @@ globalThis.loadPyodide = async function(config = {}) {
    *
    * @param {string} name Name of the Javascript module to remove
    */
-  Module.unregisterJsModule = function(name) {
+  Module.unregisterJsModule = function (name) {
     Module.pyodide_py.unregister_js_module(name);
   };
-  // clang-format on
 
   /**
    * Convert the Javascript object to a Python object as best as possible.
@@ -705,10 +734,9 @@ globalThis.loadPyodide = async function(config = {}) {
    * conversion.
    * @returns {PyProxy} The object converted to Python.
    */
-  Module.toPy = function(obj, depth = -1) {
+  Module.toPy = function (obj, depth = -1) {
     // No point in converting these, it'd be dumb to proxy them so they'd just
     // get converted back by `js2python` at the end
-    // clang-format off
     switch (typeof obj) {
       case "string":
       case "number":
@@ -717,7 +745,6 @@ globalThis.loadPyodide = async function(config = {}) {
       case "undefined":
         return obj;
     }
-    // clang-format on
     if (!obj || Module.isPyProxy(obj)) {
       return obj;
     }
@@ -727,9 +754,7 @@ globalThis.loadPyodide = async function(config = {}) {
     try {
       obj_id = Module.hiwire.new_value(obj);
       py_result = Module.__js2python_convert(obj_id, new Map(), depth);
-      // clang-format off
-      if(py_result === 0){
-        // clang-format on
+      if (py_result === 0) {
         Module._pythonexc2js();
       }
       if (Module._JsProxy_Check(py_result)) {
@@ -738,9 +763,7 @@ globalThis.loadPyodide = async function(config = {}) {
         // return Module.pyproxy_new(py_result);
       }
       result = Module._python2js(py_result);
-      // clang-format off
       if (result === 0) {
-        // clang-format on
         Module._pythonexc2js();
       }
     } finally {
@@ -754,13 +777,13 @@ globalThis.loadPyodide = async function(config = {}) {
    * @param jsobj {any} Object to test.
    * @returns {bool} Is ``jsobj`` a :any:`PyProxy`?
    */
-  Module.isPyProxy = function(jsobj) {
-    return !!jsobj && jsobj.$$ !== undefined && jsobj.$$.type === 'PyProxy';
+  Module.isPyProxy = function (jsobj) {
+    return !!jsobj && jsobj.$$ !== undefined && jsobj.$$.type === "PyProxy";
   };
 
   Module.locateFile = (path) => baseURL + path;
 
-  let moduleLoaded = new Promise(r => Module.postRun = r);
+  let moduleLoaded = new Promise((r) => (Module.postRun = r));
 
   const scriptSrc = `${baseURL}pyodide.asm.js`;
 
@@ -794,7 +817,7 @@ def temp(Module):
 
   Module.saveState = () => Module.pyodide_py._state.save_state();
   Module.restoreState = (state) =>
-      Module.pyodide_py._state.restore_state(state);
+    Module.pyodide_py._state.restore_state(state);
 
   Module.init_dict.get("temp")(Module);
   // Module.runPython works starting from here!
@@ -816,8 +839,9 @@ def temp(Module):
 
 if (globalThis.languagePluginUrl) {
   console.warn(
-      "languagePluginUrl is deprecated and will be removed in version 0.18.0, " +
-      "instead use loadPyodide({ indexURL : <some_url>})");
+    "languagePluginUrl is deprecated and will be removed in version 0.18.0, " +
+      "instead use loadPyodide({ indexURL : <some_url>})"
+  );
 
   /**
    * A deprecated parameter that specifies the Pyodide ``indexURL``. If present,
@@ -840,6 +864,7 @@ if (globalThis.languagePluginUrl) {
    * @type Promise
    * @deprecated Will be removed in version 0.18.0
    */
-  globalThis.languagePluginLoader =
-      loadPyodide({indexURL : globalThis.languagePluginUrl});
+  globalThis.languagePluginLoader = loadPyodide({
+    indexURL: globalThis.languagePluginUrl,
+  });
 }
diff --git a/src/webworker.js b/src/webworker.js
index 212b68ebe..0a8d6e3af 100644
--- a/src/webworker.js
+++ b/src/webworker.js
@@ -1,10 +1,10 @@
-importScripts('./pyodide.js')
+importScripts("./pyodide.js");
 
-onmessage = async function(e) {
+onmessage = async function (e) {
   try {
     const data = e.data;
     for (let key of Object.keys(data)) {
-      if (key !== 'python') {
+      if (key !== "python") {
         // Keys other than python must be arguments for the python script.
         // Set them on self, so that `from js import key` works.
         self[key] = data[key];
@@ -12,15 +12,15 @@ onmessage = async function(e) {
     }
 
     if (typeof self.__pyodideLoading === "undefined") {
-      await loadPyodide({indexURL : '{{ PYODIDE_BASE_URL }}'});
+      await loadPyodide({ indexURL: "{{ PYODIDE_BASE_URL }}" });
     }
     await self.pyodide.loadPackagesFromImports(data.python);
     let results = await self.pyodide.runPythonAsync(data.python);
-    self.postMessage({results});
+    self.postMessage({ results });
   } catch (e) {
     // if you prefer messages with the error
-    self.postMessage({error : e.message + '\n' + e.stack});
+    self.postMessage({ error: e.message + "\n" + e.stack });
     // if you prefer onerror events
     // setTimeout(() => { throw err; });
   }
-}
+};
diff --git a/tools/apply-lint.sh b/tools/apply-lint.sh
index 51b4b7daf..595b9cc71 100755
--- a/tools/apply-lint.sh
+++ b/tools/apply-lint.sh
@@ -1,5 +1,11 @@
-FILES="$(git ls-files --others --exclude-standard '*.c' '*.h' '*.js')"
-FILES+=" $(git diff HEAD --name-only '*.c' '*.h' '*.js')"
+FILES="$(git ls-files --others --exclude-standard '*.js')"
+FILES+=" $(git diff HEAD --name-only '*.js')"
+if [[ $FILES != " " ]]; then
+    prettier --write ${FILES}
+fi
+
+FILES="$(git ls-files --others --exclude-standard '*.c' '*.h')"
+FILES+=" $(git diff HEAD --name-only '*.c' '*.h')"
 if [[ $FILES != " " ]]; then
     clang-format-6.0 -i -verbose ${FILES}
 fi
diff --git a/tools/clang-format-precommit.sh b/tools/clang-format-precommit.sh
index 2caf01576..d40745c90 100755
--- a/tools/clang-format-precommit.sh
+++ b/tools/clang-format-precommit.sh
@@ -1,9 +1,15 @@
 #!/bin/bash
-FILES=$(git diff --cached --name-only *.c *.h *.js)
-if [ -z "$FILES" ]; then
-    exit 0
+FILES=$(git diff --cached --name-only *.c *.h)
+if [ -n "$FILES" ]; then
+    echo hi
+    # Change files, stage changes
+    clang-format-6.0 -verbose -i $FILES
+    git add $FILES
 fi
 
-# Change files, stage changes
-clang-format-6.0 -verbose -i $FILES
-git add $FILES
+FILES=$(git diff --cached --name-only *.js)
+if [ -n "$FILES" ]; then
+    # Change files, stage changes
+    ./node_modules/.bin/prettier --write $FILES
+    git add $FILES
+fi