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moodlehq/moodle-local\_importmapshim
====================================

A Moodle local plugin that injects the es-module-shims polyfill to enable import map support on browsers that lack native support.

v1.0.0(yesterday)00GPL-3.0-or-laterPHPPHP &gt;=8.1

Since Mar 24Pushed yesterdayCompare

[ Source](https://github.com/moodlehq/moodlehq-local_importmapshim)[ Packagist](https://packagist.org/packages/moodlehq/moodle-local_importmapshim)[ RSS](/packages/moodlehq-moodle-local-importmapshim/feed)WikiDiscussions main Synced today

READMEChangelog (1)Dependencies (2)Versions (2)Used By (0)

Import Map Shim (`local_importmapshim`)
=======================================

[](#import-map-shim-local_importmapshim)

A Moodle local plugin that injects the [es-module-shims](https://github.com/guybedford/es-module-shims) polyfill into every page, enabling import map support for browsers that do not natively support the feature.

Why this plugin exists
----------------------

[](#why-this-plugin-exists)

Moodle 5.2+ adopted **ES module import maps** as the foundation for its React-based UI. An import map is a JSON block in the HTML page that tells the browser how to resolve bare module specifiers like:

```
import React from 'react'; // browser needs to know where 'react' actually lives
```

Moodle core added the import map mechanism but did not ship a polyfill for browsers that lack native support. Older browsers — and some versions of Firefox until recently — do not support import maps natively, causing the entire React-based UI to silently break for those users.

This plugin injects [es-module-shims](https://github.com/guybedford/es-module-shims) into every Moodle page **before** any import map or ES module is parsed. The shim works transparently: on browsers that already support import maps natively it steps aside and does nothing; on older browsers it intercepts module loading and emulates the feature.

LayerWho provides itImport map definition + React modulesMoodle coreNative import map supportModern browsersImport map support on older browsersThis plugin (via es-module-shims)Requirements
------------

[](#requirements)

- Moodle 5.2 or later
- PHP 8.1 or later

Installation
------------

[](#installation)

### Using Git

[](#using-git)

From your Moodle root directory, clone the plugin into the `public/local/` subdirectory:

```
cd /path/to/moodle
git clone https://github.com/moodlehq/moodle-local_importmapshim public/local/importmapshim
```

Then visit **Site administration &gt; Notifications** to complete the installation.

### Manual

[](#manual)

1. Download the plugin archive.
2. Extract it so the plugin folder is at `/public/local/importmapshim/`.
3. Log in as an administrator and visit **Site administration &gt; Notifications**.

How it works
------------

[](#how-it-works)

The plugin hooks into Moodle's `before_standard_top_of_body_html_generation` hook (priority 1000) to inject a `` tag that loads the `es-module-shims` polyfill early in the page lifecycle — before any import map or ES module scripts are evaluated.

The polyfill is served by a dedicated PSR-7 route controller (`/shims/{revision}`) that applies appropriate HTTP cache headers:

ModeBehaviourDevelopment (`$CFG->cachejs = false`)Short-lived headers, no ETag, 2-second expiryProduction`Cache-Control: public, max-age=31536000, immutable` with ETag and 304 supportUpdating the bundled polyfill
-----------------------------

[](#updating-the-bundled-polyfill)

The `es-module-shims` library can be updated by running the helper script:

```
node local/importmapshim/scripts/update-esm-shims.mjs
```

For example:

```
node local/importmapshim/scripts/update-esm-shims.mjs 2.7.0
```

This downloads the specified release, updates `js/es-module-shims.js`, and updates the version metadata in `thirdpartylibs.xml`.

License
-------

[](#license)

This plugin is licensed under the [GNU General Public License v3 or later](LICENSE.md).

###  Health Score

39

—

LowBetter than 87% of packages

Maintenance100

Actively maintained with recent releases

Popularity0

Limited adoption so far

Community7

Small or concentrated contributor base

Maturity42

Maturing project, gaining track record

 Bus Factor1

Top contributor holds 100% of commits — single point of failure

How is this calculated?**Maintenance (25%)** — Last commit recency, latest release date, and issue-to-star ratio. Uses a 2-year decay window.

**Popularity (30%)** — Total and monthly downloads, GitHub stars, and forks. Logarithmic scaling prevents top-heavy scores.

**Community (15%)** — Contributors, dependents, forks, watchers, and maintainers. Measures real ecosystem engagement.

**Maturity (30%)** — Project age, version count, PHP version support, and release stability.

###  Release Activity

Cadence

Unknown

Total

1

Last Release

1d ago

### Community

Maintainers

![](https://www.gravatar.com/avatar/af50aff7bc9a1b0863806f0a384ce233451b87a1425b4b4de51aea64810ace59?d=identicon)[andrewnicols](/maintainers/andrewnicols)

![](https://www.gravatar.com/avatar/1357cc7febc619eabeafab294690e7697fe2eac160901b32860e1474e5c0ffcd?d=identicon)[meirza](/maintainers/meirza)

---

Top Contributors

[![meirzamoodle](https://avatars.githubusercontent.com/u/115134930?v=4)](https://github.com/meirzamoodle "meirzamoodle (3 commits)")

---

Tags

polyfillmoodleImportmapesmlocal plugines-module-shims

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