array insertion javascript

var list = ["foo", "bar"];


list.push("baz");


["foo", "bar", "baz"] // result

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits;

function myFunction() {
  fruits.splice(2, 0, "Lemon", "Kiwi");
  document.getElementById("demo").innerHTML = fruits;
}Array.prototype.insert = function ( index, item ) {
    this.splice( index, 0, item );
};