js中数组去重方法总结

1.es6有了Set，可以通过成员唯一性去重

function sorta(arr){
        return Array.from(new Set(arr));
}
console.log(sorta([32, 4, 63, 673, 23, 77, 44, 4, 32]));

C:\Program Files\nodejs\node.exe --inspect-brk=30255 新建文本文档.js 
Debugger listening on ws://127.0.0.1:30255/22324c55-3fa6-4f27-9e3a-eced7c4226ff
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
Array(7) [32, 4, 63, 673, 23, 77, 44]

2.使用数组对象的lastIndexOf()方法。
(关于lastIndexOf():(https://www.jianshu.com/p/d75886bc6c75)

function sorta(arr){
  var newArr = [];
   for(var i=0;i<arr.length;i++){
     newArr.lastIndexOf(arr[i]) != -1 ? '' : newArr.push(arr[i]);
  }
  return newArr;
}
console.log(sorta([1,1,2,4,4,3,2,7,98,5]));
output: (7) [1, 2, 4, 3, 7, 98, 5]

3.定义新数组，存入原数组第一个元素，再将原数组元素和新数组元素比较，不同的继续push到新数组。

function sorta(arr) {
            var newArr = [arr[0]];
            for (var i = 1; i < arr.length; i++) {
                var flag = 0;
                for (let j = 0; j < newArr.length; j++) {
                    if (arr[i] === newArr[j]) {
                        flag = 1;
                        break;
                    }
                }
                if (!flag) {
                    newArr.push(arr[i]);
                }
            }
            return newArr;
        }  

4.splice()方法从数组中添加/删除重复值。

/**
 * @description
 * @author Gundam
 * @param {*} arr
 * @returns
 */
function sorta(arr) {
  var i,j;
  var k = arr.length;
  for (i = 0; i < k; i++) {
      for (j = i + 1; j < k; j++) {
          if (arr[i] == arr[j]) {
              arr.splice(j, 1);
              k--;
              j--;
          }
      }
  }
  return arr;
}
console.log(sorta([5,7,3,3,4,6,3,2,12,7,52]));
//output:Array(8) [5, 7, 3, 4, 6, 2, 12, 52]

5.使用includes()方法{ps:可搭配foreach()方法||filter()方法;}。

function sorta(arr){
  var newarr = [];
  arr.forEach(element => {
    return newarr.includes(element) ? '' : newarr.push(element);
  });
  return newarr;
}
console.log(sorta([1,23,1,23,3,4,2,5,6,3]));

C:\Program Files\nodejs\node.exe --inspect-brk=6378 新建文本文档.js 
Debugger listening on ws://127.0.0.1:6378/70fdc9eb-c8a0-4ae5-9d98-00cd2a479df9
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
Array(7) [1, 23, 3, 4, 2, 5, 6]

6.采用indexOf()获取索引查询去重

function sorta(arr) {
  var newarr = [];
  for (var i = 0; i < arr.length; i++) {
      if (newarr.indexOf(arr[i])==-1) {
          newarr.push(arr[i]);
      }
  }
  return newarr;
}
console.log(sorta([32,4,63,673,23,77,44,4,32]));

C:\Program Files\nodejs\node.exe --inspect-brk=21364 新建文本文档.js 
Debugger listening on ws://127.0.0.1:21364/138dfd0b-dcf8-4c4b-8a21-94943e6b577f
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
Array(7) [32, 4, 63, 673, 23, 77, 44]

7.利用对象属性存在与否判断，这个方法没什么意思，但是也可行

function sorta(arr) {
  var obj = {};
  var newarr = [];
  for (var i = 0; i < arr.length; i++) {
    if (!obj[arr[i]]) {
      obj[arr[i]] = 1; //标记为true
      newarr.push(arr[i]);
    }
  }
  return newarr;
}
console.log(sorta([32, 4, 63, 673, 23, 77, 44, 4, 32]));

C:\Program Files\nodejs\node.exe --inspect-brk=3114 新建文本文档.js 
Debugger listening on ws://127.0.0.1:3114/fe648dc8-2ef6-4f46-a428-41c87bcb7e2e
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
Array(7) [32, 4, 63, 673, 23, 77, 44]

以上方法我都验证没有问题，希望对你有所帮助。