Minimal Node.js support (#1691)

.circleci/config.yml

@@ -220,7 +220,7 @@ jobs:
           command: |
             cd src/js
             npx tsd
-            npm i
+            npm install
             npm test
 
 

docs/project/changelog.md

@@ -45,6 +45,8 @@ substitutions:
   using {any}`pyodide.registerComlink`
   {pr}`1642`
 
+- {{ Enhancement }} Pyodide can experimentally be used in Node.js {pr}`1689`
+
 ## Standard library
 
 - The following standard library modules are now available as standalone packages

emsdk/patches/fix_file_packager_node.patch

@@ -0,0 +1,47 @@
+commit fb4b3c3a955e73fe20f930fb73588c0ad7a446e5
+Author: Sam Clegg <sbc@chromium.org>
+Date:   Thu Jun 3 09:42:51 2021 -0700
+
+    Add support for `--preload-file` in Node.js (#11785)
+
+    Note: this is included in emscripten 2.O.24
+
+diff --git a/emsdk/upstream/emscripten/tools/file_packager.py b/emsdk/upstream/emscripten/tools/file_packager.py
+index cd70b4b7d..ace6d6b2c 100755
+--- a/emsdk/upstream/emscripten/tools/file_packager.py
++++ b/emsdk/upstream/emscripten/tools/file_packager.py
+@@ -525,14 +525,12 @@ def main():
+     remote_package_size = os.path.getsize(package_name)
+     remote_package_name = os.path.basename(package_name)
+     ret += r'''
+-      var PACKAGE_PATH;
++      var PACKAGE_PATH = '';
+       if (typeof window === 'object') {
+         PACKAGE_PATH = window['encodeURIComponent'](window.location.pathname.toString().substring(0, window.location.pathname.toString().lastIndexOf('/')) + '/');
+-      } else if (typeof location !== 'undefined') {
+-        // worker
++      } else if (typeof process === 'undefined' && typeof location !== 'undefined') {
++        // web worker
+         PACKAGE_PATH = encodeURIComponent(location.pathname.toString().substring(0, location.pathname.toString().lastIndexOf('/')) + '/');
+-      } else {
+-        throw 'using preloaded data can only be done on a web page or in a web worker';
+       }
+       var PACKAGE_NAME = '%s';
+       var REMOTE_PACKAGE_BASE = '%s';
+@@ -716,6 +714,16 @@ def main():
+ 
+     ret += r'''
+       function fetchRemotePackage(packageName, packageSize, callback, errback) {
++        if (typeof process === 'object') {
++          require('fs').readFile(packageName, function(err, contents) {
++            if (err) {
++              errback(err);
++            } else {
++              callback(contents.buffer);
++            }
++          });
++          return;
++        }
+         var xhr = new XMLHttpRequest();
+         xhr.open('GET', packageName, true);
+         xhr.responseType = 'arraybuffer';

src/js/load-pyodide.js

@@ -9,8 +9,17 @@ let baseURL;
  */
 export async function initializePackageIndex(indexURL) {
   baseURL = indexURL;
-  let response = await fetch(`${indexURL}packages.json`);
-  Module.packages = await response.json();
+  if (typeof process !== "undefined" && process.release.name !== "undefined") {
+    const fs = await import("fs");
+    fs.readFile(`${indexURL}packages.json`, (err, data) => {
+      if (err) throw err;
+      let response = JSON.parse(data);
+      Module.packages = response;
+    });
+  } else {
+    let response = await fetch(`${indexURL}packages.json`);
+    Module.packages = await response.json();
+  }
 }
 
 ////////////////////////////////////////////////////////////

src/js/package.json

@@ -12,6 +12,9 @@
   },
   "type": "module",
   "scripts": {
-    "test": "mocha"
+    "test": "mocha --timeout 15000"
+  },
+  "dependencies": {
+    "node-fetch": "^2.6.1"
   }
 }

src/js/test/pyodide.test.js

@@ -0,0 +1,30 @@
+import assert from "assert";
+import { loadPyodide } from "../pyodide.js";
+
+import fetch from "node-fetch";
+
+describe("Pyodide", () => {
+  let pyodide;
+  it("loadPyodide", async () => {
+    pyodide = await loadPyodide({ indexURL: "../../build/" });
+  });
+  it("runPython", async () => {
+    let res = pyodide.runPython("1+1");
+    assert.equal(res, 2);
+  });
+  it("loadPackage", async () => {
+    await pyodide.loadPackage(["micropip"]);
+  });
+  it("micropip.install", async () => {
+    // TODO: micropip currently requires a globally defined fetch function
+    global.fetch = fetch;
+    await pyodide.runPythonAsync(
+      'import micropip; await micropip.install("snowballstemmer")'
+    );
+    let res = pyodide.runPython(`
+    import snowballstemmer
+    len(snowballstemmer.stemmer('english').stemWords(['A', 'node', 'test']))
+    `);
+    assert.equal(res, 3);
+  });
+});