2 var isArray = require('../internals/is-array');
3 var toLength = require('../internals/to-length');
4 var bind = require('../internals/function-bind-context');
6 // `FlattenIntoArray` abstract operation
7 // https://tc39.github.io/proposal-flatMap/#sec-FlattenIntoArray
8 var flattenIntoArray = function (target, original, source, sourceLen, start, depth, mapper, thisArg) {
9 var targetIndex = start;
11 var mapFn = mapper ? bind(mapper, thisArg, 3) : false;
14 while (sourceIndex < sourceLen) {
15 if (sourceIndex in source) {
16 element = mapFn ? mapFn(source[sourceIndex], sourceIndex, original) : source[sourceIndex];
18 if (depth > 0 && isArray(element)) {
19 targetIndex = flattenIntoArray(target, original, element, toLength(element.length), targetIndex, depth - 1) - 1;
21 if (targetIndex >= 0x1FFFFFFFFFFFFF) throw TypeError('Exceed the acceptable array length');
22 target[targetIndex] = element;
32 module.exports = flattenIntoArray;