How can I add new array elements at the beginning of an array in Javascript?

Question

I have a need to add or prepend elements at the beginning of an array.

For example, if my array looks like below:

[23, 45, 12, 67]

Answer 1

Cheatsheet to prepend new element(s) into the array

1. Array#unshift

const list = [23, 45, 12, 67];

list.unshift(34);

console.log(list); // [34, 23, 45, 12, 67];

2. Array#splice

const list = [23, 45, 12, 67];

list.splice(0, 0, 34);

console.log(list); // [34, 23, 45, 12, 67];

3. ES6 spread...

const list = [23, 45, 12, 67];
const newList = [34, ...list];

console.log(newList); // [34, 23, 45, 12, 67];

4. Array#concat

const list = [23, 45, 12, 67];
const newList = [32].concat(list);

console.log(newList); // [34, 23, 45, 12, 67];

Note: In each of these examples, you can prepend multiple items by providing more items to insert.