1. 遍历递归

  1. ~function(){
  2.     let myFlat = function() {
  3.       let res = [],
  4.       _this = this,
  5.       fn = arr => {
  6.           for(let i = 0;i<arr.length;i++) {
  7.             let item = arr[i];
  8.           if(Array.isArray(item)) {
  9.               fn(item);
  10.             continue;
  11.           }
  12.           res.push(item)
  13.         }
  14.       }
  15.       fn(_this);
  16.     return res;
  17.   }
  18.   Array.prototype.myFlat = myFlat
  19. }()

2.toString

  1. function flatten(arr) {
  2.     return arr.toString().split(',')
  3. }

3.reduce

  1. function flatten(arr) {
  2.     if(!Array.isArray(arr)) {
  3.       throw Error('not array')
  4.   }
  5.   return arr.reduce((prev,next) => {
  6.     return prev.concat(Array.isArray(next)? flatten(next) : next)
  7.   },[])
  8. }

4.扩展运算符

  1. function flatten(arr) {
  2.     if(!Array.isArray(arr)) {
  3.       throw Error('not array')
  4.   }
  5.   while(arr.some(item => Array.isArray(item))) {
  6.       arr = [].concat(...arr)
  7.   }
  8.   return arr
  9. }

5. Array.prototype.flat

  1. arr.flat(Infinity)