JSFiddle - React, Tailwind, and code Playground

HTML

<span id='foo'></span>

JavaScript

var mybag = []; 
  mybag[0] = 20.50; 
  mybag[1] = 10.13;
  mybag[3] = 0;
  var result = +mybag.reduce(function(a, b) { return a + +b }, 0).toFixed(2);
  
	document.getElementById('foo').textContent = result + ' ' + typeof result;