数组去重的几种简单办法

数组的查询方法去重

    <script>

        var arr = [1,2,5,46,2,1,3,5,6,1,2,5,4,2,2,4,3,1,2,3,5,5]
        var arr1 = [ ];
        for( var i = 0 ; i < arr.length ; i++){
            if(arr1.indexOf(arr[i]) === -1 ){
                arr1.push(arr[i]);
            }
        }
        console.log(arr1);
    </script>

先排序再循环遍历去重

    <script>

        var arr = [1,2,3,5,47,9,5,2,3,6,4,2,5,1,2,]
        arr.sort(function(a,b){
            return a - b ;
        })
        for( var  i = 0 ; i < arr.length - 1 ; i++){
            if(arr[i] === arr[i + 1]){
                arr.splice(i+1 , 1);
                i--;     
            }   
        }
        console.log(arr);
    </script>

双重for循环去重

    <script>
          

          var arr = [ 1  , 1 , 2 , 3 , 5 , 2 , 1 , 3 , 4 ];
          for( var i = 0 ; i < arr.length - 1 ; i++){
              for(var j = i + 1 ; j < arr.length ; j++){
                  if(arr[i] === arr[j]){
                      arr.splice(j , 1);
                  }
              }


          }
          console.log(arr);
    </script> 

利用对象的属性不重复去重

    <script>
        var arr = [ 1,2,3,4,5,7,2,1,3,5,6,5];
        var obj = {};
        var arr1 = [];
        for( var i= 0 ; i< arr.length ; i++){
            //对象中没有该属性,则会返回一个undefined
            if(obj[arr[i]] === undefined){
                 //nice 是随机写的,写什么都无所谓
                obj[arr[i]] = 'nice';
            }
        }
        //把字符串类型转化成为数字类型
        for(var a in obj){
            arr1.push(a - 0);
        }
    
        console.log(arr1);

    </script>