common-js

v0.3.8

Published

3 years ago

module.exports and module.import for browsers too

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webreflection

require module exports import async browser

CommonJS + module.import()

This module aim is to bring both CommonJS like module behavior on Web browsers, and a promise based module.import(path) to both browsers and NodeJS.

Yes, it resolves paths relatively to the current one!

Yes, it is secure too, check the CSP enabled page!

Don't miss the introductory blog post about this idea!

Browser Example

<!doctype html>
<html>
  <script
    id="common-js"
    data-main="/js-browser/main.js"
    src="common.js"
  ></script>
</html>

Having a single script with id="common-js" is all it takes to be able to load asynchronously any other file or module.

The main entry point /js-browser/main.js will resolve relative paths from /js-browser/ folder.

Its loaded modules will resolve their own imported paths from where they've been loaded, and so on. The same goes for NodeJS, it's indeed same logic behind require.

// /js-browser/main.js loading /js-browser/test.js
module.import('./test').then(function (test) {
  test('Hello CommonJS!');
  // will output:
  // Hello CommonJS!
  // from /js-browser/test.js
});

// the /js-browser/test.js content
module.exports = function (message) {
  alert(message + '\nfrom ' + module.filename);
};

Load multiple modules at once

Promise.all([
  module.import('./a'),
  module.import('//cdn.something.com/cool.js'),
  module.import('../sw.js'),
  module.import('/root/too.js')
]).then(function (modules) {
  const [a, cool, sw, too] = modules;
});

Exporting modules asynchronously

// an async example of /js-browser/test.js content
// for the /js-browser/main.js file nothing changes
module.exports = new Promise(function (resolve) {
  setTimeout(
    resolve,
    1000,
    function (message) {
      alert(message + '\nfrom ' + module.filename);
    }
  );
});

Compatibility

You can test your target directly through the live test page. What I could test was the following:

Mobile Android 2+, iOS5+, WP7+, BBOS7+, FFOS1+, WebOS2+, Kindle Paper & Fire

Desktop Chrome, FF, Safari, Opera, IE9+ (theoretically IE8 too but it needs few polyfills upfront)

What else?

The synchronous require and both __filename and __dirname are also exposed, but nothing else from NodeJS core is available. You are responsible for loading all the modules you need, possibly only when you need them.

F.A.Q

Does it load every time? It uses a cache, like NodeJS does. If you load same module twice, even from different relative paths, it'll use the cached one.
Why on the module? There are scripts, script type module, importScripts, a dynamic import proposal, you name it ... this one actually works and it's backward compatible with modules that don't care about this solution existing.
Why not ES2015 modules? Because those, so far, never truly solved anything. Actually, ES6 modules created more problems due inability to require modules at runtime and/or on the browser.
Is there a CDN I can use to test? There is always one for npm modules. https://unpkg.com/common-js@latest should be already OK.
Is this using eval? No. It's using a technique that is even compatible with highest security standards such Content Security Policy

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