Delete array element based on elements in an array as index

Question

Suppose I have an array as

let arr1 = [0,2] This is always sorted

Note: These elements in array represent indexes to be deleted from another array.

I have another array as:

let arrOvj = [1,4,6,7,21,17,12]

I want to delete element of arrObj, based on indexes present in arr1.

So after deletion expected OP should be,

[4,7,21,17,12].

So how can I achieve this.

I tried as:

for(let i=0;i<arr1.length;i++){
   arrObj.splice(arr1[i],1)
}

But this is giving incorrect result.

Example: If arr1=[0]

It deletes first two elements instead of deleting element at index 0 of arrObj.

What other alternative can I follow so it deletes from provided index value only

Please let me know if anyone need any further information.

Also, after deleting, the index will change, so you could run arr1 backwards — ariel, Oct 13 '21 at 02:30
Sorry actually I tried with splice itself but mistakenly typed wrong over here — Sushant Rad, Oct 13 '21 at 02:31
@ariel Sorry I didn't understand, could you please show it in code if possible or any article. — Sushant Rad, Oct 13 '21 at 02:33
Does this answer your question? [Remove multiple elements from array in Javascript/jQuery](https://stackoverflow.com/questions/9425009/remove-multiple-elements-from-array-in-javascript-jquery) — Heretic Monkey, Feb 10 '22 at 13:46

score 4 · Accepted Answer · edited Oct 13 '21 at 21:04

4

You can loop backwards over the indices to delete so that elements will never be shifted into a location that has not been already processed.

let arr1 = [0,2] 
let arrOvj = [1,4,6,7,21,17,12]
for(let i = arr1.length - 1; i >= 0; i--) arrOvj.splice(arr1[i], 1);
console.log(arrOvj);

edited Oct 13 '21 at 21:04

answered Oct 13 '21 at 02:33

Unmitigated

score 2 · Answer 2 · answered Oct 13 '21 at 02:30

Other way of doing it is using the filter method on the array and removing out the corresponding indexes as follows:

let arrObj = [1,4,6,7,21,17,12]
let indexes = [0,2]

let newArr = arrObj.filter((ele, index) => !indexes.includes(index));

console.log(newArr);

DecPK · Answer 3 · 2021-10-13T02:54:12.067

1

You can use splice and reduceRight here.

let arr1 = [0, 2];
let arrOvj = [1, 4, 6, 7, 21, 17, 12];

arrOvj = arr1.reduceRight((a, c) => (a.splice(c, 1), a), arrOvj);

console.log(arrOvj);

edited Oct 13 '21 at 02:54

answered Oct 13 '21 at 02:33

DecPK

3 Answers3