数组去重的几种方式

    var arr = [1,1,‘1‘,2,2,‘2‘,‘c‘,‘c‘,‘d‘]
    function returnArr () {
      var newArr = [arr[0]]
      arr.forEach((item,index) => {
        var flg = true
        newArr.forEach((item2,index2) => {
          if (item  === item2) {
            flg = false
          }
        })
        // 当在新数组中没有当前值时进行插入
        if (flg) {
          newArr.push(item)
        }
      })
      return newArr
    }
    console.log(returnArr())

    function deleteArray( arr ){
      for( var i = 0; i < arr.length; i++ ){
        for( var j = i+1; j < arr.length; j++ ){
          if( arr[i] === arr[j] ){
            arr.splice(j, 1);
            j--;
          }
        }
      }
      return arr;
    }
    console.log(deleteArray(arr))

    function uniq(){
      var arr2 = []
      for(var i = 0; i < arr.length; i++){
        if(arr2.indexOf(arr[i]) == -1){
          arr2.push(arr[i])
        }
      }
      return arr2
    }
    console.log(uniq())

Array.from(new Set(arr))