1 var bind = require('../internals/function-bind-context');
2 var call = require('../internals/function-call');
3 var aConstructor = require('../internals/a-constructor');
4 var toObject = require('../internals/to-object');
5 var lengthOfArrayLike = require('../internals/length-of-array-like');
6 var getIterator = require('../internals/get-iterator');
7 var getIteratorMethod = require('../internals/get-iterator-method');
8 var isArrayIteratorMethod = require('../internals/is-array-iterator-method');
9 var aTypedArrayConstructor = require('../internals/array-buffer-view-core').aTypedArrayConstructor;
11 module.exports = function from(source /* , mapfn, thisArg */) {
12 var C = aConstructor(this);
13 var O = toObject(source);
14 var argumentsLength = arguments.length;
15 var mapfn = argumentsLength > 1 ? arguments[1] : undefined;
16 var mapping = mapfn !== undefined;
17 var iteratorMethod = getIteratorMethod(O);
18 var i, length, result, step, iterator, next;
19 if (iteratorMethod && !isArrayIteratorMethod(iteratorMethod)) {
20 iterator = getIterator(O, iteratorMethod);
23 while (!(step = call(next, iterator)).done) {
27 if (mapping && argumentsLength > 2) {
28 mapfn = bind(mapfn, arguments[2]);
30 length = lengthOfArrayLike(O);
31 result = new (aTypedArrayConstructor(C))(length);
32 for (i = 0; length > i; i++) {
33 result[i] = mapping ? mapfn(O[i], i) : O[i];