JSFiddle - React, Tailwind, and code Playground

HTML

<output id="crumMenuOutput"></output>
<br />
<br />
<button type="button" id="test">Ny takst</button>

JavaScript

$(document).ready(function () {

     var menuArray = new Array;

     menuArray.push("test1"); // add test data to array

     $("button").click(function () {

         menuArray.push("test2"); // fail to add data on button click
         alert($(this).attr('id')); // just at test to see function working
         if (menuArray.lenght !== 0) {
             $.each(menuArray, function (i, val) {
                 if (i == menuArray.length - 1) var spacer = "";
                 else var spacer = " > ";
                 $('#crumMenuOutput').append(val + spacer);
             });
         }


     });

 });