JSFiddle - React, Tailwind, and code Playground

by Luis Perez

HTML

<div id="Output"></div>

JavaScript

function insertAt(array, index) {
        var arrayToInsert = Array.prototype.splice.apply(arguments, [2]);
        Array.prototype.splice.apply(array, [index, 0].concat(arrayToInsert));
        return array;
    }
    
    function insertArrayAt(array, index, arrayToInsert) {
        Array.prototype.splice.apply(array, [index, 0].concat(arrayToInsert));
        return array;
    }

var arr = ["A", "B", "C"];
$("#Output").append("arr before insertAt(): " + JSON.stringify(arr) + "<br />"); // output: A, B, C
insertAt(arr, 1, "x", "y", "z");
$("#Output").append("arr after insertAt(): " + JSON.stringify(arr) + "<br />"); // output: A, x, y, z, B, C

var arr2 = ["A", "B", "C"];
$("#Output").append("arr2 before insertArrayAt(): " + JSON.stringify(arr2) + "<br />"); // output: A, B, C
insertArrayAt(arr2, 1, ["x", "y", "z"]);
$("#Output").append("arr2 before insertArrayAt(): " + JSON.stringify(arr2) + "<br />"); // output: A, x, y, z, B, C