arr.flat数组扁平化+去重排序

之前最简单的写法

let arr = [ [1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14] ] ] ], 10];
let newarr = Array.from(new Set(arr.toString().split(','))).sort((a,b)=>a-b)
//["1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14"]

arr.toString()  //"1,2,2,3,4,5,5,6,7,8,9,11,12,12,13,14,10"
.split(',')    //["1", "2", "2", "3", "4", "5", "5", "6", "7", "8", "9", "11", "12", "12", "13", "14", "10"]s
.sort((a,b)=>a-b)      //["1", "2", "2", "3", "4", "5", "5", "6", "7", "8", "9", "10", "11", "12", "12", "13", "14"]

//new Set 去重  > 对象
//Array.from() 对象>数组

es10的arr.flat

Array.from(new Set(arr.flat(Infinity))).sort((a,b)=>{ return a-b})

可以看出

arr.flat() === arr.toString().split(',')  === 数组扁平化

封装一个flat,方式一

Array.prototype.flat=function(){
  var arr = [];
  this.forEach( k =>{
    if(Array.isAttay(K)){
        arr=arr.concat(k.flat())  //如果是数组，继续循环
    }else{
        arr.push(k)
    }
  })
  return arr
}

封装一个flat,方式二

Array.prototype.flat = funtion(){
  return this.toString()  
              //"1,2,2,3,4,5,5,6,7,8,9,11,12,12,13,14,10"
              .split(',')    
              //["1", "2", "2", "3", "4", "5", "5", "6", "7", "8", "9", "11", "12", "12", "13", "14", "10"]s
              .sort((a,b)=>a-b)      
              //["1", "2", "2", "3", "4", "5", "5", "6", "7", "8", "9", "10", "11", "12", "12", "13", "14"]
}
console.log([1,[2,[3,4]]].flat())//[1, 2, 3, 4]