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- 'use strict';
- var isArray = require('../internals/is-array');
- var toLength = require('../internals/to-length');
- var bind = require('../internals/function-bind-context');
- // `FlattenIntoArray` abstract operation
- // https://tc39.github.io/proposal-flatMap/#sec-FlattenIntoArray
- var flattenIntoArray = function (target, original, source, sourceLen, start, depth, mapper, thisArg) {
- var targetIndex = start;
- var sourceIndex = 0;
- var mapFn = mapper ? bind(mapper, thisArg, 3) : false;
- var element;
- while (sourceIndex < sourceLen) {
- if (sourceIndex in source) {
- element = mapFn ? mapFn(source[sourceIndex], sourceIndex, original) : source[sourceIndex];
- if (depth > 0 && isArray(element)) {
- targetIndex = flattenIntoArray(target, original, element, toLength(element.length), targetIndex, depth - 1) - 1;
- } else {
- if (targetIndex >= 0x1FFFFFFFFFFFFF) throw TypeError('Exceed the acceptable array length');
- target[targetIndex] = element;
- }
- targetIndex++;
- }
- sourceIndex++;
- }
- return targetIndex;
- };
- module.exports = flattenIntoArray;
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