mirror of https://github.com/jkjoy/sunpeiwen.git
29 lines
830 B
JavaScript
29 lines
830 B
JavaScript
'use strict';
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// https://tc39.github.io/proposal-setmap-offrom/
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var $export = require('./_export');
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var aFunction = require('./_a-function');
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var ctx = require('./_ctx');
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var forOf = require('./_for-of');
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module.exports = function (COLLECTION) {
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$export($export.S, COLLECTION, { from: function from(source /* , mapFn, thisArg */) {
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var mapFn = arguments[1];
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var mapping, A, n, cb;
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aFunction(this);
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mapping = mapFn !== undefined;
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if (mapping) aFunction(mapFn);
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if (source == undefined) return new this();
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A = [];
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if (mapping) {
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n = 0;
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cb = ctx(mapFn, arguments[2], 2);
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forOf(source, false, function (nextItem) {
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A.push(cb(nextItem, n++));
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});
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} else {
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forOf(source, false, A.push, A);
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}
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return new this(A);
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} });
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};
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