JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
<div id="diff">

</div>

JavaScript

var a = {
	name:"donor",
  label:"Donor Data File (donor)",
  pattern:"^donor(\\.[a-zA-Z0-9]+)?\\.txt(?:\\.gz|\\.bz2)?$"
  };
var b = {
	name:"donor",
  label:"Donor Data File (donor)",
  pattern:"^donor(\\.[a-zA-Z0-9]+)?\\.txt(?:\\.gz)?$"
}
console.log(_.difference(a,b));