jQuery addClass example
Change class name on click in jQuery
HTML
<pre id='pre1'>test</pre>
<pre id='pre2'></pre>
JavaScript
// find elements
const pre1 = $("#pre1");
const pre2 = $("#pre2");
var d1 = $.Deferred();
var d2 = $.Deferred();
$.when(d1).then(function(name){
pre1.text(name)
}).fail(() => pre1.text('FAIL'));
setTimeout(function() {
d1.reject();
}, 2000);