doc: add require(esm) explainer

pages/modules/require-esm.md

@@ -0,0 +1,109 @@
+---
+authors: vinayakPandey7
+---
+
+# Requiring ES modules from CommonJS
+
+Node.js can load an ES module with `require()`. That is often called **require(esm)**.
+
+It lets CommonJS code (`require` / `module.exports`) load packages that only ship ESM (`export` / `import`), without converting the whole app to ESM first.
+
+The feature is unflagged on current release lines, so you do not need `--experimental-require-module`. It was marked no longer experimental in Node.js 25.4.0.
+
+## Versions
+
+Use a Node.js version that has unflagged support:
+
+- **Node.js 20.19.0** or later on the v20 line
+- **Node.js 22.12.0** or later
+- Any later major (23+)
+
+A common `engines` range is:
+
+```json
+{
+  "engines": {
+    "node": "^20.19.0 || >=22.12.0"
+  }
+}
+```
+
+On older versions, `require()` of an ES module throws `ERR_REQUIRE_ESM`.
+
+## Quick example
+
+`distance.mjs`:
+
+```mjs
+export function distance(a, b) {
+  return Math.sqrt((b.x - a.x) ** 2 + (b.y - a.y) ** 2);
+}
+```
+
+`app.js` (CommonJS):
+
+```cjs
+const { distance } = require('./distance.mjs');
+
+console.log(distance({ x: 0, y: 0 }, { x: 3, y: 4 }));
+// 5
+```
+
+`require()` of an ES module returns the **module namespace object**, the same shape as a static `import`, including a `.default` property when the module has a default export.
+
+`point.mjs`:
+
+```mjs
+export default class Point {
+  constructor(x, y) {
+    this.x = x;
+    this.y = y;
+  }
+}
+```
+
+```cjs
+const point = require('./point.mjs');
+
+console.log(point);
+// [Module: null prototype] { default: [class Point], __esModule: true }
+
+const Point = point.default;
+```
+
+The ES module may also export the name `"module.exports"` so `require()` returns that value directly. See the [API docs](https://nodejs.org/api/modules.html#loading-ecmascript-modules-using-require).
+
+## When `require()` can load ESM
+
+The module must be **fully synchronous** (no top-level `await`), and one of these must be true:
+
+1. The file ends in `.mjs`
+2. The file ends in `.js` and the closest `package.json` has `"type": "module"`
+3. The file ends in `.js`, the closest `package.json` is not `"type": "commonjs"`, and the source uses ES module syntax
+
+Graph modules loaded from that ESM file can use `import` as usual.
+
+## FAQ
+
+### Can the ES module use top-level `await`?
+
+No. Top-level `await` makes the module async. `require()` is synchronous, so that load fails. Use dynamic `import()` if you need TLA.
+
+### Is `require(esm)` the same as `import()`?
+
+No. `import()` is async and returns a promise. `require(esm)` runs synchronously and returns the namespace (or `module.exports` interop) immediately. Prefer `import` in new ESM code; use `require(esm)` when you are still in CommonJS.
+
+### Do I still need dual CJS+ESM builds?
+
+Often no, if your consumers are on the versions above. Publishing a single ESM graph that is `require()`-able is simpler and avoids [dual-package hazard](/learn/modules/publishing-a-package). Check your support policy first.
+
+### How do I tell if a package is ESM?
+
+Look at `"type": "module"` and `"exports"` in its `package.json`. If `require()` used to throw `ERR_REQUIRE_ESM` and you are now on a supported Node.js, try again without extra flags.
+
+## Learn more
+
+- [Loading ECMAScript modules using `require()`](https://nodejs.org/api/modules.html#loading-ecmascript-modules-using-require) — API details
+- [Determining the module system](https://nodejs.org/api/packages.html#determining-module-system)
+- [Publishing a package](/learn/modules/publishing-a-package)
+- [package-examples: making ESM require-able](https://github.com/nodejs/package-examples/blob/main/guide/04-cjs-esm-interop/require-esm/README.md) — worked examples

site.json

@@ -333,6 +333,10 @@
     {
       "groupName": "Modules",
       "items": [
+        {
+          "link": "/learn/modules/require-esm",
+          "label": "Requiring ES modules from CommonJS"
+        },
         {
           "link": "/learn/modules/how-to-use-streams",
           "label": "How to use streams"