bendc/supportsES6.js

Created August 25, 2016 08:05

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Test if ES6 is ~fully supported

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supportsES6.js

	var supportsES6 = function() {
	try {
	new Function("(a = 0) => a");
	return true;
	}
	catch (err) {
	return false;
	}
	}();

Author

bendc commented Aug 25, 2016

Load your untranspiled ES6 file for modern browsers:

if (supportsES6) {
  var script = document.createElement("script");
  script.src = "my-es6-file.js";
  document.head.appendChild(script);
}

rik commented Aug 25, 2016

I think this requires some performance testing since you can't benefit from browsers "parse ahead" behaviour to download the JS file as soon as possible.

triblondon commented Aug 26, 2016

The ~ is pretty critical here, unless we know that for every browser, the last part of ES6 to be supported was either arrows or default args?

triblondon commented Aug 26, 2016

@rik optimising for the modern browsers, you could <link rel=preload> it

Author

bendc commented Aug 26, 2016

@triblondon Yup, the critical test is the a = 0 (all browsers supporting default parameters have a fairly complete support of ES6 -- for example, Edge 13 will be rejected by this test despite a decent ES6 coverage).

kenberkeley commented Mar 1, 2019 •

edited

<html>
<head>
  <script>
  if (typeof Symbol === 'undefined') {
    document.write('<script crossorigin="anonymous" src="https://polyfill.io/v3/polyfill.min.js?features=es6,es7&flags=gated"><\/script>')
  }
  </script>
</head>
<body>
</body>
</html>

cai-zhuo commented Mar 6, 2023 •

edited

@triblondon Yup, the critical test is the a = 0 (all browsers supporting default parameters have a fairly complete support of ES6 -- for example, Edge 13 will be rejected by this test despite a decent ES6 coverage).

I wanna know how to prove “all browsers supporting default parameters have a fairly complete support of ES6”
Thankfully， if you can show links or refs

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