add item in javascript array code example

Example 1: javascript insert item into array

var colors=["red","blue"];
var index=1;

//insert "white" at index 1
colors.splice(index, 0, "white");   //colors =  ["red", "white", "blue"]

Example 2: how to push items in array in javascript

let items = [1, 2, 3]
items.push(4); // items = [1, 2, 3, 4]