add a fix for FF99+ Array.prototype.includes broken on sparse arrays

CHANGELOG.md

@@ -1,6 +1,6 @@
 ## Changelog
 ##### Unreleased
-- Nothing
+- Added a fix for FF99+ `Array.prototype.includes` broken on sparse arrays
 
 ##### 3.22.2 - 2022.04.21
 - Fixed `URLSearchParams` in IE8- that was broken in the previous release

packages/core-js-compat/src/data.mjs

@@ -211,7 +211,8 @@ export const data = {
   'es.array.includes': {
     chrome: '53',
     edge: '14',
-    firefox: '48',
+    // FF99+ broken on sparse arrays
+    // firefox: '48',
     safari: '10.0',
   },
   'es.array.index-of': {

packages/core-js/modules/es.array.includes.js

@@ -1,11 +1,17 @@
 'use strict';
 var $ = require('../internals/export');
 var $includes = require('../internals/array-includes').includes;
+var fails = require('../internals/fails');
 var addToUnscopables = require('../internals/add-to-unscopables');
 
+// FF99+ bug
+var BROKEN_ON_SPARSE = fails(function () {
+  return !Array(1).includes();
+});
+
 // `Array.prototype.includes` method
 // https://tc39.es/ecma262/#sec-array.prototype.includes
-$({ target: 'Array', proto: true }, {
+$({ target: 'Array', proto: true, forced: BROKEN_ON_SPARSE }, {
   includes: function includes(el /* , fromIndex = 0 */) {
     return $includes(this, el, arguments.length > 1 ? arguments[1] : undefined);
   }

tests/compat/tests.js

@@ -352,7 +352,8 @@ GLOBAL.tests = {
   },
   'es.array.from': SAFE_ITERATION_CLOSING_SUPPORT,
   'es.array.includes': function () {
-    return Array.prototype[Symbol.unscopables].includes;
+    return Array(1).includes()
+      && Array.prototype[Symbol.unscopables].includes;
   },
   'es.array.index-of': function () {
     try {