javascript insert between array items code example

Example 1: add array to array javascript

// SPREAD OPERATOR
 const list1 = ["pepe", "luis", "rua"];
 const list2 = ["rojo", "verde", "azul"];
 const newList = [...list1, ...list2];
 // ["pepe", "luis", "rua", "rojo", "verde", "azul"]

Example 2: array insertion javascript

Array.prototype.insert = function ( index, item ) {
    this.splice( index, 0, item );
};