js数组去重

原文地址：http://www.jb51.net/article/121410.htm

js数组根据对象中的元素去重

var arr2 = [
  { name: "name", num: "1" },
  { name: "name2", num: "11" },
  { name: "name3", num: "12" },
  { name: "name", num: "13" },
  { name: "name2", num: "1" },
  { name: "name6", num: "12" }
]
function arrayUnique2(arr, name) {
  var hash = {};
  return arr.reduce(function (item, next) {
    hash[next[name]] ? '' : hash[next[name]] = true && item.push(next);
    return item;
  }, []);
}
console.log(arrayUnique2(arr2, "name"));
console.log(arrayUnique2(arr2, "num"));

当数组的长度变得很大时,三、四、五、六、七相对来说会更有优势，而方法八的执行速度似乎一直垫底。

测试方法三执行速度

var arr = 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,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6,7,4,1,1,2,3,5,3,1,5,6];
var time3 = new Date().getTime();
function unique3(arr){
 var res = [];
 var obj = {};
 for(var i=0; i<arr.length; i++){
  if( !obj[arr[i]] ){
   obj[arr[i]] = 1;
   res.push(arr[i]);
  }
 } 
 return res;
}

console.log('------------方法三---------------');
console.log( unique3(arr) );
console.log('3所花时间： ' + (new Date().getTime() - time3));

Methods 1: 思路：定义一个新数组，并存放原数组的第一个元素，然后将元素组一一和新数组的元素对比，若不同则存放在新数组中。

function unique(arr){
 var res = [arr[0]];
 for(var i=1; i<arr.length; i++){
  var repeat = false;
  for(var j=0; j<res.length; j++){
   if(arr[i] === res[j]){
    repeat = true;
    break;
   }
  }
  if(!repeat){
   res.push(arr[i]);
  }
 }
 return res;
}
console.log('------------方法一---------------');

console.log(unique([1,1,2,3,5,3,1,5,6,7,4]));

Methods 2: 思路：先将原数组排序，在与相邻的进行比较，如果不同则存入新数组。

function unique2(arr){
 var arr2 = arr.sort();
 var res = [arr2[0]];
 for(var i=1; i<arr2.length; i++){
  if(arr2[i] !== res[res.length-1]){
   res.push(arr2[i]);
  }
 } 
 return res;
}
console.log('------------方法二---------------');
console.log(unique2([1,1,2,3,5,3,1,5,6,7,4]));

Methods 3: 利用对象属性存在的特性，如果没有该属性则存入新数组。

function unique3(arr){
 var res = [];
 var obj = {};
 for(var i=0; i<arr.length; i++){
  if( !obj[arr[i]] ){
   obj[arr[i]] = 1;
   res.push(arr[i]);
  }
 } 
 return res;
}
console.log('------------方法三---------------');
console.log(unique3([1,1,2,3,5,3,1,5,6,7,4]));

Methods 4: 利用数组的indexOf下标属性来查询。

function unique4(arr){
 var res = [];
 for(var i=0; i<arr.length; i++){
  if(res.indexOf(arr[i]) == -1){
   res.push(arr[i]);
  }
 }
 return res;
}
console.log('------------方法四---------------');
console.log(unique4([1,1,2,3,5,3,1,5,6,7,4]));

Methods 5: 利用数组原型对象上的includes方法。

function unique5(arr){
 var res = [];
 
 for(var i=0; i<arr.length; i++){
  if( !res.includes(arr[i]) ){ // 如果res新数组包含当前循环item
   res.push(arr[i]);
  }
 }
 return res;
}
console.log('------------方法五---------------');
console.log(unique5([1,1,2,3,5,3,1,5,6,7,4]));

Methods 6: 利用数组原型对象上的 filter 和 includes方法。

function unique6(arr){
 var res = [];
 
 res = arr.filter(function(item){
  return res.includes(item) ? '' : res.push(item);
 });
 return res;
}

console.log('------------方法六---------------');
console.log(unique6([1,1,2,3,5,3,1,5,6,7,4]));

Methods 7: 利用数组原型对象上的 forEach 和 includes方法。

function unique7(arr){
 var res = [];
 
 arr.forEach(function(item){
  res.includes(item) ? '' : res.push(item);
 }); 
 return res;
}

console.log('------------方法七---------------');
console.log(unique7([1,1,2,3,5,3,1,5,6,7,4]));

Methods 8: 利用数组原型对象上的 splice 方法。

function unique8(arr){
 var i,
  j,
  len = arr.length; 
 for(i = 0; i < len; i++){
  for(j = i + 1; j < len; j++){
   if(arr[i] == arr[j]){
    arr.splice(j,1);
    len--;
    j--;
   }
  }
 }
 return arr;
}

console.log('------------方法八---------------');
console.log(unique8([1,1,2,3,5,3,1,5,6,7,4]));

Methods 9: 利用数组原型对象上的 lastIndexOf 方法。

function unique9(arr){
 var res = []; 
 for(var i=0; i<arr.length; i++){
  res.lastIndexOf(arr[i]) !== -1 ? '' : res.push(arr[i]);
 }
 return res;
}

console.log('------------方法九---------------');
console.log(unique9([1,1,2,3,5,3,1,5,6,7,4]));

Methods 10: 利用 ES6的set 方法。

function unique10(arr){
 //Set数据结构，它类似于数组，其成员的值都是唯一的
 return Array.from(new Set(arr)); // 利用Array.from将Set结构转换成数组
}

console.log('------------方法十---------------');
console.log(unique10([1,1,2,3,5,3,1,5,6,7,4]));
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