append in array only what is missing javascript code example

Example 1: js add element to array

var fruits = [ "Orange", "Apple", "Mango"];

fruits.push("Banana");

Example 2: javascript append element to array

// initialize array
var arr = [
  "Hi",
  "Hello",
  "Bonjour"
];

// append new value to the array
arr.push("Hola");

console.log(arr);