Create new array without impacting values from old array

Question

I'm trying to create a copy of existing array and remove some items from array copy without impacting the original. I've tried this :

var new_arr = old_arr; //when I remove from new array the items from old array are also removed

How do I create entirely new copy of the existing array?

Update :

When I do this :

var new_arr = old_arr.slice();

then later :

new_arr[0].shift();
new_arr[1].shift();

The items from old_array get removed. This is a two dimensional array.

Answer 1

You can use two methods, this:

function clone (src) {
    return JSON.parse(JSON.stringify(src));
}

or this:

var newArray = oldArray.slice();

Answer 2

A newer solution to do this is to use 'from' like this:

const newArr = Array.from(oldArr);

But this is a shallow copy and if nested elements are mutated they will project in the new created array with from. Best solution then would be to use

const newArr = JSON.parse(JSON.stringify(oldArr));

but also that method doesn't ensure all. If for example an element of the array contains a function like n => ++n then it will be null after using the JSON methods so best solution is deepClone and for that full explanation I refer to

Creating JavaScript Arrays