debian-mirror-gitlab/core-js/modules/es.array.concat.js

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2019-09-25 13:30:05 +05:30
'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;
}
});