1.删除数组中的某个指定元素

let arr = [1,2,3];
const ind = arr.indexOf(2);
if(ind>-1){
     arr.splice(ind,1);
}
console.log(arr);//[1, 3]

2.删除数组中的指定数组对象

1)遍历数组

let arr=[1,2,2,3];
const delArr=['2','4'];
delArr.forEach((value,index)=>{
  
})

2）filter

let arr = [1, 3, 5, 7, 9];
arr = arr.filter(item => item !== 5&&item !== 7);
console.log(arr);//[1,3,9]

或

let arr = [1,,1,2,3, 3, 5, 7, 9];
let delArr=[1,3]
arr = arr.filter(item => {
    let bool=true;
    delArr.forEach(itemChild=>{
        if(item==itemChild){
          bool=false;
         }
    })
   if(bool){
         return item  
    }
});
console.log(arr);//[2,5,7,9]

3.删除重复元素

1）new set()  

let arr3=[1,2,2,3,4,5,6,7,8,8,8,8];
let n=Array.from(new Set(arr3));//或  n=[...new Set(arr)]
console.log(n);//[1, 2, 3, 4, 5, 6, 7, 8]

2)indexOf

function fn(arr){
   let newArr = []
   arr.forEach((val)=>{
         if(newArr.indexOf(val) == -1){
              newArr.push(val)
          }
    })    
   return newArr  
}    
fn([1,2,3,2]);//[1,2,3]

3)for

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)
         }
    }
}    

4)sort排序后去重

function fn(arr){
   let newArr = []
   arr.sort((a,b)=>{
       return a-b
   })
   arr.forEach((val,index)=>{
       if(val != arr[index+1]){
            newArr.push(val)
       }
   })
   return newArr
}