[6a3a178] | 1 | 'use strict';
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| 2 | var $ = require('../internals/export');
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| 3 | var fails = require('../internals/fails');
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| 4 | var isArray = require('../internals/is-array');
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| 5 | var isObject = require('../internals/is-object');
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| 6 | var toObject = require('../internals/to-object');
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| 7 | var toLength = require('../internals/to-length');
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| 8 | var createProperty = require('../internals/create-property');
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| 9 | var arraySpeciesCreate = require('../internals/array-species-create');
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| 10 | var arrayMethodHasSpeciesSupport = require('../internals/array-method-has-species-support');
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| 11 | var wellKnownSymbol = require('../internals/well-known-symbol');
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| 12 | var V8_VERSION = require('../internals/engine-v8-version');
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| 13 |
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| 14 | var IS_CONCAT_SPREADABLE = wellKnownSymbol('isConcatSpreadable');
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| 15 | var MAX_SAFE_INTEGER = 0x1FFFFFFFFFFFFF;
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| 16 | var MAXIMUM_ALLOWED_INDEX_EXCEEDED = 'Maximum allowed index exceeded';
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| 17 |
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| 18 | // We can't use this feature detection in V8 since it causes
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| 19 | // deoptimization and serious performance degradation
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| 20 | // https://github.com/zloirock/core-js/issues/679
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| 21 | var IS_CONCAT_SPREADABLE_SUPPORT = V8_VERSION >= 51 || !fails(function () {
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| 22 | var array = [];
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| 23 | array[IS_CONCAT_SPREADABLE] = false;
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| 24 | return array.concat()[0] !== array;
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| 25 | });
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| 26 |
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| 27 | var SPECIES_SUPPORT = arrayMethodHasSpeciesSupport('concat');
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| 28 |
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| 29 | var isConcatSpreadable = function (O) {
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| 30 | if (!isObject(O)) return false;
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| 31 | var spreadable = O[IS_CONCAT_SPREADABLE];
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| 32 | return spreadable !== undefined ? !!spreadable : isArray(O);
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| 33 | };
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| 34 |
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| 35 | var FORCED = !IS_CONCAT_SPREADABLE_SUPPORT || !SPECIES_SUPPORT;
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| 36 |
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| 37 | // `Array.prototype.concat` method
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| 38 | // https://tc39.es/ecma262/#sec-array.prototype.concat
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| 39 | // with adding support of @@isConcatSpreadable and @@species
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| 40 | $({ target: 'Array', proto: true, forced: FORCED }, {
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| 41 | // eslint-disable-next-line no-unused-vars -- required for `.length`
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| 42 | concat: function concat(arg) {
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| 43 | var O = toObject(this);
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| 44 | var A = arraySpeciesCreate(O, 0);
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| 45 | var n = 0;
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| 46 | var i, k, length, len, E;
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| 47 | for (i = -1, length = arguments.length; i < length; i++) {
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| 48 | E = i === -1 ? O : arguments[i];
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| 49 | if (isConcatSpreadable(E)) {
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| 50 | len = toLength(E.length);
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| 51 | if (n + len > MAX_SAFE_INTEGER) throw TypeError(MAXIMUM_ALLOWED_INDEX_EXCEEDED);
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| 52 | for (k = 0; k < len; k++, n++) if (k in E) createProperty(A, n, E[k]);
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| 53 | } else {
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| 54 | if (n >= MAX_SAFE_INTEGER) throw TypeError(MAXIMUM_ALLOWED_INDEX_EXCEEDED);
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| 55 | createProperty(A, n++, E);
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| 56 | }
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| 57 | }
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| 58 | A.length = n;
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| 59 | return A;
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| 60 | }
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| 61 | });
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