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31 lines
982 B
31 lines
982 B
2 years ago
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'use strict';
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// https://tc39.github.io/proposal-setmap-offrom/
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var bind = require('../internals/function-bind-context');
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var call = require('../internals/function-call');
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var aCallable = require('../internals/a-callable');
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var aConstructor = require('../internals/a-constructor');
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var iterate = require('../internals/iterate');
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var push = [].push;
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module.exports = function from(source /* , mapFn, thisArg */) {
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var length = arguments.length;
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var mapFn = length > 1 ? arguments[1] : undefined;
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var mapping, array, n, boundFunction;
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aConstructor(this);
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mapping = mapFn !== undefined;
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if (mapping) aCallable(mapFn);
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if (source == undefined) return new this();
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array = [];
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if (mapping) {
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n = 0;
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boundFunction = bind(mapFn, length > 2 ? arguments[2] : undefined);
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iterate(source, function (nextItem) {
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call(push, array, boundFunction(nextItem, n++));
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});
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} else {
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iterate(source, push, { that: array });
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}
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return new this(array);
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};
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