How to update an array everytime when pushing values

Question

I am facing difficulty while pushing the values inside the array.

Suppose I have array like this

const arr = ["tom", "harry", "mike"];

What I want to achieve is, when I am pushing values inside this array. I don't want to append that value in the array, but create a new array with the appended value and not change the old array.

Answer 1

Push is meant to be modify the array so I think you can take advantage of spread operator to create new array with new value added instead of modifying the old one.

let arr = ["j", "d", "s"];
let newFrontAdd = ["new value", ...arr]
let newRearAdd = [ ...arr, "new value"]

console.log("original array : ", arr);
console.log("added value at front : ", newFrontAdd);
console.log("added value at rear : ", newRearAdd);

Answer 2

Everything you need to know about arrays is here: https://www.w3schools.com/js/js_arrays.asp

When talking about arrays, the term push means to append.

const arr = ["tom", "harry", "mike"];
arr.push("swapnil")
// arr: ["tom", "harry", "mike", "swapnil"]

If you want to set a particular index, you may do that like so:

const arr = ["tom", "harry", "mike"];
arr[1] = "swapnil"
// arr: ["tom", "swapnil", "mike"]

If you'd like to overwrite the entire array, you can't use const. Use let (or var) instead.

let arr = ["tom", "harry", "mike"];
arr = ["swapnil", "steve]
// arr: ["swapnil", "steve"]