how to pushvar in var js code example

Example 1: how to push items in array in javascript

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

Example 2: js add array items to array

var arrayA = [1, 2];
var arrayB = [3, 4];
var newArray = arrayA.concat(arrayB);