数组去重的方法

数组去重的方法

1.双层for循环去重

let arr=[1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0,9]
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)
    }
  }
}
console.log(arr);

2.利用ES6中的Set()去重

let arr=[1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0,9]
var newArr=new Set(arr)
console.log(newArr);
// 或者
let arr=[1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0,9]
var newArr=[...new Set(arr)]
console.log(newArr);

3.indexOf()去重

let arr=[1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0,9]
let newArr=[]
arr.forEach((val)=>{
  if(newArr.indexOf(val)==-1) {
    newArr.push(val)
  }
})
console.log(newArr);

4.sort()去重

let arr=[1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0,9]
let newArr=[]
arr.sort((a,b)=>{
  return a-b
})
arr.forEach((val,index)=>{
  if(val!=arr[index+1]) {
    newArr.push(val)
  }
})
console.log(newArr);

5.includes()去重

let arr=[1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0,9]
let newArr=[]
for(var i=0;i<arr.length;i++) {
  if(!newArr.includes(arr[i])) {
    newArr.push(arr[i])
  }
}
console.log(newArr);

6.Map()去重

let arr=[1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0,9]
let map = new Map()
let newArr=[]
for(var i=0;i<arr.length;i++) {
  if(map.has(arr[i])) {
    map.set(arr[i],true)
  }else {
    map.set(arr[i],false)
    newArr.push(arr[i])
  }
}
console.log(newArr);

7.利用对象属性不能重复的特点进行去重

let arr=[1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0,9]
var newArr=[]
var obj={}
for(var i = 0;i<arr.length;i++) {
  if(!obj[arr[i]]) {
    newArr.push(arr[i])
    obj[arr[i]]=1
  }else {
    obj[arr[i]]++
  }
}
console.log(newArr);