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