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es.array.slice.js
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es.array.slice.js
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'use strict';
var $ = require('../internals/export');
var isObject = require('../internals/is-object');
var isArray = require('../internals/is-array');
var toAbsoluteIndex = require('../internals/to-absolute-index');
var toLength = require('../internals/to-length');
var toIndexedObject = require('../internals/to-indexed-object');
var createProperty = require('../internals/create-property');
var wellKnownSymbol = require('../internals/well-known-symbol');
var arrayMethodHasSpeciesSupport = require('../internals/array-method-has-species-support');
var arrayMethodUsesToLength = require('../internals/array-method-uses-to-length');
var HAS_SPECIES_SUPPORT = arrayMethodHasSpeciesSupport('slice');
var USES_TO_LENGTH = arrayMethodUsesToLength('slice', { ACCESSORS: true, 0: 0, 1: 2 });
var SPECIES = wellKnownSymbol('species');
var nativeSlice = [].slice;
var max = Math.max;
// `Array.prototype.slice` method
// https://tc39.github.io/ecma262/#sec-array.prototype.slice
// fallback for not array-like ES3 strings and DOM objects
$({ target: 'Array', proto: true, forced: !HAS_SPECIES_SUPPORT || !USES_TO_LENGTH }, {
slice: function slice(start, end) {
var O = toIndexedObject(this);
var length = toLength(O.length);
var k = toAbsoluteIndex(start, length);
var fin = toAbsoluteIndex(end === undefined ? length : end, length);
// inline `ArraySpeciesCreate` for usage native `Array#slice` where it's possible
var Constructor, result, n;
if (isArray(O)) {
Constructor = O.constructor;
// cross-realm fallback
if (typeof Constructor == 'function' && (Constructor === Array || isArray(Constructor.prototype))) {
Constructor = undefined;
} else if (isObject(Constructor)) {
Constructor = Constructor[SPECIES];
if (Constructor === null) Constructor = undefined;
}
if (Constructor === Array || Constructor === undefined) {
return nativeSlice.call(O, k, fin);
}
}
result = new (Constructor === undefined ? Array : Constructor)(max(fin - k, 0));
for (n = 0; k < fin; k++, n++) if (k in O) createProperty(result, n, O[k]);
result.length = n;
return result;
}
});