Many polyfills are missing

[chenyulun]

[type]: A bug report

What

Core-js test cases are compared，It turns out that Polyfill-Library is missing a lot

Details

Chrome 41
https://github.com/chenyulun/polyfill-test

polyfill-test

polyfill.io VS core-js3.9.1

Use the link calculated below

 const featuresList = [
  'default',
  'es2015',
  'es2016',
  'es2017',
  'es2018',
  'es2019',
  'es2020',
  'es2021',
  'globalThis',
  'queueMicrotask',
  // 'URL',
  'URL.prototype.toJSON',
  'URLSearchParams',
  // 'DOMTokenList',
  'DOMTokenList.prototype.@@iterator',
  'DOMTokenList.prototype.forEach',
  'DOMTokenList.prototype.replace',
  'NodeList.prototype.@@iterator',
  'NodeList.prototype.forEach',
  'URL.prototype.toJSON',
  'URLSearchParams',
  'Reflect',
  'Reflect.apply',
  'Reflect.construct',
  'Reflect.defineProperty',
  'Reflect.deleteProperty',
  'Reflect.get',
  'Reflect.getOwnPropertyDescriptor',
  'Reflect.getPrototypeOf',
  'Reflect.has',
  'Reflect.isExtensible',
  'Reflect.ownKeys',
  'Reflect.preventExtensions',
  'Reflect.set',
  'Reflect.setPrototypeOf',
  // 'setImmediate',
]
const features = encodeURIComponent(featuresList.join(','))
console.log(`https://polyfill.io/v3/polyfill.min.js?features=${features}`)
// https://polyfill.io/v3/polyfill.min.js?features=default%2Ces2015%2Ces2016%2Ces2017%2Ces2018%2Ces2019%2Ces2020%2Ces2021%2CglobalThis%2CqueueMicrotask%2CURL.prototype.toJSON%2CURLSearchParams%2CDOMTokenList.prototype.%40%40iterator%2CDOMTokenList.prototype.forEach%2CDOMTokenList.prototype.replace%2CNodeList.prototype.%40%40iterator%2CNodeList.prototype.forEach%2CURL.prototype.toJSON%2CURLSearchParams%2CReflect%2CReflect.apply%2CReflect.construct%2CReflect.defineProperty%2CReflect.deleteProperty%2CReflect.get%2CReflect.getOwnPropertyDescriptor%2CReflect.getPrototypeOf%2CReflect.has%2CReflect.isExtensible%2CReflect.ownKeys%2CReflect.preventExtensions%2CReflect.set%2CReflect.setPrototypeOf

Core-js compiles the full code minified.js

The patch gap in the lower version of the phone is too big

Test steps

~ yarn
~ yarn http-server -p 8085 -c-1

Choose a lower version of Chrome /41

Open a browser to http://ip:8085/tests/index.html

2. Add the core - js - 3.19.1
   open file tests/index.html

+ <script src='./minified.js'></script>
<script src='./tests.js'></script>

You can see it's basically all green

3. add polyfill.io
   tests/index.html

- <script src='./minified.js'></script>
+ <script src="https://polyfill.io/v3/polyfill.min.js?features=default%2Ces2015%2Ces2016%2Ces2017%2Ces2018%2Ces2019%2Ces2020%2Ces2021%2CglobalThis%2CqueueMicrotask%2CURL.prototype.toJSON%2CURLSearchParams%2CDOMTokenList.prototype.%40%40iterator%2CDOMTokenList.prototype.forEach%2CDOMTokenList.prototype.replace%2CNodeList.prototype.%40%40iterator%2CNodeList.prototype.forEach%2CURL.prototype.toJSON%2CURLSearchParams%2CReflect%2CReflect.apply%2CReflect.construct%2CReflect.defineProperty%2CReflect.deleteProperty%2CReflect.get%2CReflect.getOwnPropertyDescriptor%2CReflect.getPrototypeOf%2CReflect.has%2CReflect.isExtensible%2CReflect.ownKeys%2CReflect.preventExtensions%2CReflect.set%2CReflect.setPrototypeOf"></script>
<script src='./tests.js'></script>

Ignore esNext， Many polyfills are defective，Especially when it comes to symbols
example

new URL('http://a#б').hash === '#%D0%B1' // chrome95 and core-js:true polyfill.io: false
1 / [1].indexOf(1, -0) > 0 // chrome95 and core-js: true polyfill.io: false
new Int8Array(null) // 
[].at //
Array.prototype[Symbol.unscopables].find //

[mhassan1]

i think it would be helpful to have individual issues for each of these defective polyfills, with the appropriate level of detail. i would be happy to help pick up some of that work.

[zloirock]

@chenyulun if you wanna use core-js test suite, it's much better to use /tests/tests instead of /tests/compat since /tests/compat is oriented only to detection of basic and known issues of native implementations.