js数组去重常见的方法汇总(7种)

 var arr = [1,9,8,8,7,2,5,3,3,3,2,3,1,4,5,444,55,22];
  console.log(arr);   
  function noRepeat(arr){
    var newArr = [...new Set(arr)]; //利用了Set结构不能接收重复数据的特点
    return newArr
  }
 
  var arr2 = noRepeat(arr)
  console.log(arr2); 

var arr = ['apple','apps','pear','apple','orange','apps'];
 
console.log(arr)    
  var newArr = arr.filter(function(item,index){
     return arr.indexOf(item) === index;  // 因为indexOf 只能查找到第一个  
  });
 
console.log(newArr); 

 var arr = [1,9,8,8,7,2,5,3,3,3,2,3,1,4,5,444,55,22];
 function noRepeat(arr) {
		//定义一个新的临时数组 
		var newArr=[]; 
		//遍历当前数组 
		for(var i=0;i<arr.length;i  ) {
		  //如果当前数组的第i已经保存进了临时数组，那么跳过，
		  //否则把当前项push到临时数组里面 
		  if(newArr.indexOf(arr[i]) === -1) {  //indexOf() 判断数组中有没有字符串值，如果没有则返回 -1 
		     newArr.push(arr[i]);
		  }
    	}
    return newArr
  }
  var arr2 = noRepeat(arr);
  console.log(arr2);  

 var arr = [1,9,8,8,7,2,5,3,3,3,2,3,1,4,5,444,55,22];
 console.log(arr);    
 function noRepeat(arr) {
        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);
                    j--;
                }
            }
        }
        return arr;
 }
 var arr2 = noRepeat(arr);
 console.log(arr2);  

 var arr = [1,9,8,8,7,2,5,3,3,3,2,3,1,4,5,444,55,22];
    console.log(arr)    
    function noRepeat(arr) {
        var newArr = [];
        for (var i = 0; i < arr.length; i  ) {
            if (arr.indexOf(arr[i]) == i) {
              newArr.push(arr[i]);
            }
        }
        return newArr;
    }
   var arr2 = noRepeat(arr);
   console.log(arr2);  

var arr = [1,9,8,8,7,2,5,3,3,3,2,3,1,4,5,444,55,22];
console.log(arr);    
function noRepeat(arr){
   for (var i = 0; i < arr.length; i  ) {
       for (var j = 0; j < arr.length; j  ) {
           if (arr[i] == arr[j] && i != j) { //将后面重复的数删掉
              arr.splice(j, 1);
            }
       }
    }
    return arr;
}
var arr2  = noRepeat(arr);
console.log(arr2);   

 var arr = [1,9,8,8,7,2,5,3,3,3,2,3,1,4,5,444,55,22];
    function noRepeat(arr) {
      let newArr = [];
      for(i=0; i<arr.length; i  ){
        if(!newArr.includes(arr[i])){
            newArr.push(arr[i])
        }
      }
     return newArr
   }
 console.log(noRepeat(arr));