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@ebidel
Last active September 4, 2023 13:56
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Feature detect ES modules: both static import and dynamic import()
<!--
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>
@Mouvedia
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Mouvedia commented Feb 3, 2021

console.log('This browser DOES NOT support <script type="module">');

This is wrong.
e.g. Safari 10.1 supports type="module" but not the nomodule attribute
see https://gist.github.com/samthor/64b114e4a4f539915a95b91ffd340acc

@erikt9
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erikt9 commented Dec 7, 2021

A more concise supportsStaticImport script:

function supportsStaticImport() {
    return 'noModule' in HTMLScriptElement.prototype;
}

@rugk
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rugk commented Dec 8, 2021

@erikt9 feel free to submit this as an answer to the Stackoverflow question linked above.

@mindhells
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https://developer.mozilla.org/en-US/docs/Web/API/HTMLScriptElement

function checkModuleSupport() {
  if ('supports' in HTMLScriptElement) {
    return HTMLScriptElement.supports('module');
  }
  return 'noModule' in document.createElement('script');
}

@rugk
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rugk commented Mar 18, 2022

@mindhells you feel also free to submit this as an answer to the Stackoverflow question linked above.

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