| 'use strict'; |
| var $ = require('../internals/export'); |
| var fails = require('../internals/fails'); |
| var isArray = require('../internals/is-array'); |
| var isObject = require('../internals/is-object'); |
| var toObject = require('../internals/to-object'); |
| var toLength = require('../internals/to-length'); |
| var createProperty = require('../internals/create-property'); |
| var arraySpeciesCreate = require('../internals/array-species-create'); |
| var arrayMethodHasSpeciesSupport = require('../internals/array-method-has-species-support'); |
| var wellKnownSymbol = require('../internals/well-known-symbol'); |
| |
| var IS_CONCAT_SPREADABLE = wellKnownSymbol('isConcatSpreadable'); |
| var MAX_SAFE_INTEGER = 0x1FFFFFFFFFFFFF; |
| var MAXIMUM_ALLOWED_INDEX_EXCEEDED = 'Maximum allowed index exceeded'; |
| |
| var IS_CONCAT_SPREADABLE_SUPPORT = !fails(function () { |
| var array = []; |
| array[IS_CONCAT_SPREADABLE] = false; |
| return array.concat()[0] !== array; |
| }); |
| |
| var SPECIES_SUPPORT = arrayMethodHasSpeciesSupport('concat'); |
| |
| var isConcatSpreadable = function (O) { |
| if (!isObject(O)) return false; |
| var spreadable = O[IS_CONCAT_SPREADABLE]; |
| return spreadable !== undefined ? !!spreadable : isArray(O); |
| }; |
| |
| var FORCED = !IS_CONCAT_SPREADABLE_SUPPORT || !SPECIES_SUPPORT; |
| |
| // `Array.prototype.concat` method |
| // https://tc39.github.io/ecma262/#sec-array.prototype.concat |
| // with adding support of @@isConcatSpreadable and @@species |
| $({ target: 'Array', proto: true, forced: FORCED }, { |
| concat: function concat(arg) { // eslint-disable-line no-unused-vars |
| var O = toObject(this); |
| var A = arraySpeciesCreate(O, 0); |
| var n = 0; |
| var i, k, length, len, E; |
| for (i = -1, length = arguments.length; i < length; i++) { |
| E = i === -1 ? O : arguments[i]; |
| if (isConcatSpreadable(E)) { |
| len = toLength(E.length); |
| if (n + len > MAX_SAFE_INTEGER) throw TypeError(MAXIMUM_ALLOWED_INDEX_EXCEEDED); |
| for (k = 0; k < len; k++, n++) if (k in E) createProperty(A, n, E[k]); |
| } else { |
| if (n >= MAX_SAFE_INTEGER) throw TypeError(MAXIMUM_ALLOWED_INDEX_EXCEEDED); |
| createProperty(A, n++, E); |
| } |
| } |
| A.length = n; |
| return A; |
| } |
| }); |