JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <input />
    <input />
    <input />
    <input />
    <button>go</button>
</div>

JavaScript

$.extend($.expr[':'], {
	    blank: function (el) {
	        return $(el).val().match(/^\s*$/);
	    }
	});

	$('button').click(function () {
	    alert($('input:blank', '#container').length);
	});