flatten-into-array.js•1.21 kB
'use strict';
var isArray = require('../internals/is-array');
var lengthOfArrayLike = require('../internals/length-of-array-like');
var doesNotExceedSafeInteger = require('../internals/does-not-exceed-safe-integer');
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) : false;
var element, elementLen;
while (sourceIndex < sourceLen) {
if (sourceIndex in source) {
element = mapFn ? mapFn(source[sourceIndex], sourceIndex, original) : source[sourceIndex];
if (depth > 0 && isArray(element)) {
elementLen = lengthOfArrayLike(element);
targetIndex = flattenIntoArray(target, original, element, elementLen, targetIndex, depth - 1) - 1;
} else {
doesNotExceedSafeInteger(targetIndex + 1);
target[targetIndex] = element;
}
targetIndex++;
}
sourceIndex++;
}
return targetIndex;
};
module.exports = flattenIntoArray;