JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="input" />
<input type="button" id="check" value="CHECK"/>

JavaScript

$(function () {
	$('#check').on('click', function () {
        var newattr = $('#input').attr("newattr");
	    if (typeof newattr !== "undefined") {
	        alert('HAS VALUE');
	    }
	    else {
	        alert('NO VALUE');
	    }
	});
});