JSFiddle - React, Tailwind, and code Playground

JavaScript

$(function(){
  function arrLen(arr) {
    var count = 0;
    
    $.each(arr, function() {
      count = count + 1;
    });
    
    return count;
  }
  
  var a = ["a", "b", "c", "d"];
  var lengthOfA = arrLen(a);
  
  $('body').html(lengthOfA)
})