如何通过拼接删除数组值？

Question

Stuck in delete array value by splice .Tried with delete and splice doesn't work..

var arr = [];
 arr[2] = 22;
 arr[5] = 3;
 arr[99] = 3343;
 for(var i in arr){
    if(i != 2){
    arr.splice(i,1);
    }
   //delete arr[i];
 }
 console.log(arr);// [2: 22, 98: 3343]
 //wanted [2:22]

I want to delete all except index 2 ,It is only delete one.

Answer 1

No need of a for loop in the splice, you may use: arr.splice(0,arr.length)

But if you want to just delete all elements just do arr=[] .

Alternative method would be to loop & pop :

while(arr.length > 0) {
    arr.pop();
}

Answer 2

In the case you might need to get a sequential item by item deletion starting from the the middle of an array you should iterate in reverse in order not to get the shifting indexes get in front of you.

 var arr = new Array(10).fill("").map((e,i) => e = "item:" +i), i = 7; console.log(JSON.stringify(arr)); while (i>2) console.log(JSON.stringify(arr.splice(i--,1))); // splice item at index i and decrease i by one console.log(JSON.stringify(arr));