Remove node-fetch fallback (#4417)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

docs/project/changelog.md

@@ -29,6 +29,10 @@ myst:
   functions.
   {pr}`4392`
 
+- {{ Breaking }} Pyodide will not fallback to `node-fetch` anymore when `fetch`
+  is not available in the Node.js < 18 environment.
+  {pr}`4417`
+
 - {{ Enhancement }} Updated `pyimport` to support `pyimport("module.attribute")`.
   {pr}`4395`
 

src/js/compat.ts

@@ -8,7 +8,6 @@ import {
 } from "./environments";
 
 let nodeUrlMod: any;
-let nodeFetch: any;
 let nodePath: any;
 let nodeVmMod: any;
 /** @private */
@@ -20,13 +19,6 @@ declare var globalThis: {
   fetch?: any;
 };
 
-const FETCH_NOT_FOUND_MSG = `\
-"fetch" is not defined, maybe you're using node < 18? \
-From Pyodide >= 0.25.0, node >= 18 is required. \
-Older versions of Node.js may work, but it is not guaranteed or supported. \
-Falling back to "node-fetch".\
-`;
-
 /**
  * If we're in node, it's most convenient to import various node modules on
  * initialization. Otherwise, this does nothing.
@@ -39,14 +31,7 @@ export async function initNodeModules() {
   // @ts-ignore
   nodeUrlMod = (await import("url")).default;
   nodeFsPromisesMod = await import("fs/promises");
-  if (globalThis.fetch) {
-    nodeFetch = fetch;
-  } else {
-    // @ts-ignore
-    console.warn(FETCH_NOT_FOUND_MSG);
-    // @ts-ignore
-    nodeFetch = (await import("node-fetch")).default;
-  }
+
   // @ts-ignore
   nodeVmMod = (await import("vm")).default;
   nodePath = await import("path");
@@ -131,7 +116,7 @@ function node_getBinaryResponse(
   }
   if (path.includes("://")) {
     // If it has a protocol, make a fetch request
-    return { response: nodeFetch(path) };
+    return { response: fetch(path) };
   } else {
     // Otherwise get it from the file system
     return {
@@ -235,7 +220,7 @@ async function nodeLoadScript(url: string) {
   }
   if (url.includes("://")) {
     // If it's a url, load it with fetch then eval it.
-    nodeVmMod.runInThisContext(await (await nodeFetch(url)).text());
+    nodeVmMod.runInThisContext(await (await fetch(url)).text());
   } else {
     // Otherwise, hopefully it is a relative path we can load from the file
     // system.

src/js/esbuild.config.mjs

@@ -59,7 +59,6 @@ const config = ({ input, output, format, name: globalName }) => ({
     "crypto",
     "fs",
     "fs/promises",
-    "node-fetch",
     "path",
     "tty",
     "url",

src/js/package.json

@@ -130,5 +130,8 @@
     "base-64": "^1.0.0",
     "ws": "^8.5.0"
   },
-  "types": "./pyodide.d.ts"
+  "types": "./pyodide.d.ts",
+  "engines": {
+    "node": ">=18.0.0"
+  }
 }