37 lines
1.5 KiB
JavaScript
37 lines
1.5 KiB
JavaScript
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'use strict';
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var ctx = require('./$.ctx')
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, $export = require('./$.export')
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, toObject = require('./$.to-object')
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, call = require('./$.iter-call')
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, isArrayIter = require('./$.is-array-iter')
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, toLength = require('./$.to-length')
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, getIterFn = require('./core.get-iterator-method');
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$export($export.S + $export.F * !require('./$.iter-detect')(function(iter){ Array.from(iter); }), 'Array', {
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// 22.1.2.1 Array.from(arrayLike, mapfn = undefined, thisArg = undefined)
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from: function from(arrayLike/*, mapfn = undefined, thisArg = undefined*/){
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var O = toObject(arrayLike)
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, C = typeof this == 'function' ? this : Array
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, $$ = arguments
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, $$len = $$.length
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, mapfn = $$len > 1 ? $$[1] : undefined
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, mapping = mapfn !== undefined
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, index = 0
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, iterFn = getIterFn(O)
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, length, result, step, iterator;
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if(mapping)mapfn = ctx(mapfn, $$len > 2 ? $$[2] : undefined, 2);
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// if object isn't iterable or it's array with default iterator - use simple case
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if(iterFn != undefined && !(C == Array && isArrayIter(iterFn))){
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for(iterator = iterFn.call(O), result = new C; !(step = iterator.next()).done; index++){
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result[index] = mapping ? call(iterator, mapfn, [step.value, index], true) : step.value;
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}
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} else {
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length = toLength(O.length);
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for(result = new C(length); length > index; index++){
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result[index] = mapping ? mapfn(O[index], index) : O[index];
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}
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}
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result.length = index;
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return result;
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}
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});
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