58 lines
2.3 KiB
JavaScript
58 lines
2.3 KiB
JavaScript
'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 lengthOfArrayLike = require('../internals/length-of-array-like');
|
|
var doesNotExceedSafeInteger = require('../internals/does-not-exceed-safe-integer');
|
|
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 V8_VERSION = require('../internals/environment-v8-version');
|
|
|
|
var IS_CONCAT_SPREADABLE = wellKnownSymbol('isConcatSpreadable');
|
|
|
|
// We can't use this feature detection in V8 since it causes
|
|
// deoptimization and serious performance degradation
|
|
// https://github.com/zloirock/core-js/issues/679
|
|
var IS_CONCAT_SPREADABLE_SUPPORT = V8_VERSION >= 51 || !fails(function () {
|
|
var array = [];
|
|
array[IS_CONCAT_SPREADABLE] = false;
|
|
return array.concat()[0] !== array;
|
|
});
|
|
|
|
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 || !arrayMethodHasSpeciesSupport('concat');
|
|
|
|
// `Array.prototype.concat` method
|
|
// https://tc39.es/ecma262/#sec-array.prototype.concat
|
|
// with adding support of @@isConcatSpreadable and @@species
|
|
$({ target: 'Array', proto: true, arity: 1, forced: FORCED }, {
|
|
// eslint-disable-next-line no-unused-vars -- required for `.length`
|
|
concat: function concat(arg) {
|
|
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 = lengthOfArrayLike(E);
|
|
doesNotExceedSafeInteger(n + len);
|
|
for (k = 0; k < len; k++, n++) if (k in E) createProperty(A, n, E[k]);
|
|
} else {
|
|
doesNotExceedSafeInteger(n + 1);
|
|
createProperty(A, n++, E);
|
|
}
|
|
}
|
|
A.length = n;
|
|
return A;
|
|
}
|
|
});
|