数组去重

用es6实现:

  let arr = [1,2,3,4,5,6,6,3,1];
  console.log(new Set(arr));// [1,2,3,4,5,6]

用es5实现:

　　

arr.filter(function(ele,index,array){
      return index === array.indexOf(ele);
  }); 
// [1,2,3,4,5,6]