add a workaround of String#{ endsWith, startsWith } MDN polyfills b…

…ugs, close #702
zloirock · Nov 26, 2019 · 7a57493 · 7a57493
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,4 +1,7 @@
 ## Changelog
+##### Unreleased
+- Added a workaround of `String#{ endsWith, startsWith }` MDN polyfills bugs, [#702](https://github.com/zloirock/core-js/issues/702)
+
 ##### 3.4.2 - 2019.11.22
 - Don't use polyfilled symbols as internal uids, a workaround for some incorrect use cases
 - `String#replaceAll` is available only in nightly FF builds

diff --git a/packages/core-js/modules/es.string.ends-with.js b/packages/core-js/modules/es.string.ends-with.js
@@ -1,16 +1,26 @@
 'use strict';
 var $ = require('../internals/export');
+var fails = require('../internals/fails');
+var getOwnPropertyDescriptor = require('../internals/object-get-own-property-descriptor').f;
 var toLength = require('../internals/to-length');
 var notARegExp = require('../internals/not-a-regexp');
 var requireObjectCoercible = require('../internals/require-object-coercible');
 var correctIsRegExpLogic = require('../internals/correct-is-regexp-logic');
+var IS_PURE = require('../internals/is-pure');
 
 var nativeEndsWith = ''.endsWith;
 var min = Math.min;
 
+var CORRECT_IS_REGEXP_LOGIC = correctIsRegExpLogic('endsWith');
+// https://github.com/zloirock/core-js/pull/702
+var MDN_POLYFILL_BUG = !IS_PURE && !CORRECT_IS_REGEXP_LOGIC && fails(function () {
+  var descriptor = getOwnPropertyDescriptor(String.prototype, 'endsWith');
+  return descriptor && !descriptor.writable;
+});
+
 // `String.prototype.endsWith` method
 // https://tc39.github.io/ecma262/#sec-string.prototype.endswith
-$({ target: 'String', proto: true, forced: !correctIsRegExpLogic('endsWith') }, {
+$({ target: 'String', proto: true, forced: !MDN_POLYFILL_BUG && !CORRECT_IS_REGEXP_LOGIC }, {
   endsWith: function endsWith(searchString /* , endPosition = @length */) {
     var that = String(requireObjectCoercible(this));
     notARegExp(searchString);

diff --git a/packages/core-js/modules/es.string.starts-with.js b/packages/core-js/modules/es.string.starts-with.js
@@ -1,16 +1,26 @@
 'use strict';
 var $ = require('../internals/export');
+var fails = require('../internals/fails');
+var getOwnPropertyDescriptor = require('../internals/object-get-own-property-descriptor').f;
 var toLength = require('../internals/to-length');
 var notARegExp = require('../internals/not-a-regexp');
 var requireObjectCoercible = require('../internals/require-object-coercible');
 var correctIsRegExpLogic = require('../internals/correct-is-regexp-logic');
+var IS_PURE = require('../internals/is-pure');
 
 var nativeStartsWith = ''.startsWith;
 var min = Math.min;
 
+var CORRECT_IS_REGEXP_LOGIC = correctIsRegExpLogic('startsWith');
+// https://github.com/zloirock/core-js/pull/702
+var MDN_POLYFILL_BUG = !IS_PURE && !CORRECT_IS_REGEXP_LOGIC && fails(function () {
+  var descriptor = getOwnPropertyDescriptor(String.prototype, 'startsWith');
+  return descriptor && !descriptor.writable;
+});
+
 // `String.prototype.startsWith` method
 // https://tc39.github.io/ecma262/#sec-string.prototype.startswith
-$({ target: 'String', proto: true, forced: !correctIsRegExpLogic('startsWith') }, {
+$({ target: 'String', proto: true, forced: !MDN_POLYFILL_BUG && !CORRECT_IS_REGEXP_LOGIC }, {
   startsWith: function startsWith(searchString /* , position = 0 */) {
     var that = String(requireObjectCoercible(this));
     notARegExp(searchString);