Sha256: c5829d54792c1b8d39984c0c1c529e15b54e474400b23db44fce7e1b017e4f94
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Versions: 13
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Stored size: 1.8 KB
Contents
'use strict';
var bind = require('../internals/function-bind-context');
var toObject = require('../internals/to-object');
var callWithSafeIterationClosing = require('../internals/call-with-safe-iteration-closing');
var isArrayIteratorMethod = require('../internals/is-array-iterator-method');
var toLength = require('../internals/to-length');
var createProperty = require('../internals/create-property');
var getIteratorMethod = require('../internals/get-iterator-method');
// `Array.from` method implementation
// https://tc39.github.io/ecma262/#sec-array.from
module.exports = function from(arrayLike /* , mapfn = undefined, thisArg = undefined */) {
var O = toObject(arrayLike);
var C = typeof this == 'function' ? this : Array;
var argumentsLength = arguments.length;
var mapfn = argumentsLength > 1 ? arguments[1] : undefined;
var mapping = mapfn !== undefined;
var iteratorMethod = getIteratorMethod(O);
var index = 0;
var length, result, step, iterator, next, value;
if (mapping) mapfn = bind(mapfn, argumentsLength > 2 ? arguments[2] : undefined, 2);
// if the target is not iterable or it's an array with the default iterator - use a simple case
if (iteratorMethod != undefined && !(C == Array && isArrayIteratorMethod(iteratorMethod))) {
iterator = iteratorMethod.call(O);
next = iterator.next;
result = new C();
for (;!(step = next.call(iterator)).done; index++) {
value = mapping ? callWithSafeIterationClosing(iterator, mapfn, [step.value, index], true) : step.value;
createProperty(result, index, value);
}
} else {
length = toLength(O.length);
result = new C(length);
for (;length > index; index++) {
value = mapping ? mapfn(O[index], index) : O[index];
createProperty(result, index, value);
}
}
result.length = index;
return result;
};
Version data entries
13 entries across 13 versions & 4 rubygems