有点意思的npm package

array-flatten

• 功能
  将一个嵌套数组展平
• 安装

npm install --save array-flatten

• 使用

//ES6
//import {flatten} from "array-flatten";

//AMD
const flatten = require("array-flatten");
const arr = ['hello',['world'],[['have'],['a'],['nice'],['day']]];

const res = flatten(arr);
console.log(res);//[ 'hello', 'world', 'have', 'a', 'nice', 'day' ]

const res2 = flatten(arr,1);
console.log(res2);//[ 'hello', 'world', [ 'have' ], [ 'a' ], [ 'nice' ], [ 'day' ] ]

• 源码
  算法，递归

'use strict'

module.exports = arrayFlatten

/**
 * Recursive flatten function with depth.
 */
function flattenWithDepth (array, result, depth) {
  for (var i = 0; i < array.length; i++) {
    var value = array[i]

    if (depth > 0 && Array.isArray(value)) {
      flattenWithDepth(value, result, depth - 1)
    } else {
      result.push(value)
    }
  }

  return result
}

/**
 * Recursive flatten function. Omitting depth is slightly faster.
 */
function flattenForever (array, result) {
  for (var i = 0; i < array.length; i++) {
    var value = array[i]

    if (Array.isArray(value)) {
      flattenForever(value, result)
    } else {
      result.push(value)
    }
  }

  return result
}

/**
 * Flatten an array, with the ability to define a depth.
 */
function arrayFlatten (array, depth) {
  if (depth == null) {
    return flattenForever(array, [])
  }

  return flattenWithDepth(array, [], depth)
}