ebidel/feature_detect_es_modules.js

## feature_detect_es_modules.js
<!--
Complete feature detection for ES modules. Covers:

1. Static import: import * from './foo.js';
2. Dynamic import(): import('./foo.js').then(module => {...});

Demo: http://jsbin.com/tilisaledu/1/edit?html,output

Thanks to @_gsathya, @kevincennis, @rauschma, @malyw for the help.
-->

<body></body>

<!-- Remember: static modules have a fallback! -->
<script type="module">
  console.log('This browser supports <script type="module">');
</script>
<script nomodule>
  console.log('This browser DOES NOT support <script type="module">');
</script>

<script>
// Feature detect static imports.
function supportsStaticImport() {
  const script = document.createElement('script');
  return 'noModule' in script;
}

// Feature detect dynamic import().
function supportsDynamicImport() {
  try {
    new Function('import("")');
    return true;
  } catch (err) {
    return false;
  }
}

// Usage.
let el = document.createElement('pre');
el.textContent = `
  Supports ES module static import: ${supportsStaticImport()}
  Supports dynamic ES module import(): ${supportsDynamicImport()}
`
document.body.appendChild(el);
</script>
	<!--
	Complete feature detection for ES modules. Covers:

	1. Static import: import * from './foo.js';
	2. Dynamic import(): import('./foo.js').then(module => {...});

	Demo: http://jsbin.com/tilisaledu/1/edit?html,output

	Thanks to @_gsathya, @kevincennis, @rauschma, @malyw for the help.
	-->

	<body></body>

	<!-- Remember: static modules have a fallback! -->
	<script type="module">
	console.log('This browser supports <script type="module">');
	</script>
	<script nomodule>
	console.log('This browser DOES NOT support <script type="module">');
	</script>

	<script>
	// Feature detect static imports.
	function supportsStaticImport() {
	const script = document.createElement('script');
	return 'noModule' in script;
	}

	// Feature detect dynamic import().
	function supportsDynamicImport() {
	try {
	new Function('import("")');
	return true;
	} catch (err) {
	return false;
	}
	}

	// Usage.
	let el = document.createElement('pre');
	el.textContent = `
	Supports ES module static import: ${supportsStaticImport()}
	Supports dynamic ES module import(): ${supportsDynamicImport()}
	`
	document.body.appendChild(el);
	</script>