JSFiddle - React, Tailwind, and code Playground

HTML

<div class="foo bar">Foo</div>
<div class="bim bar">Bar</div>

JavaScript

$("div.bar").click(function(ev) {
    var nonBarClasses = (' ' + this.className + ' ').replace(' bar ', ' ').split(/ +/);

    nonBarClasses.shift();
    nonBarClasses.pop();    

    // nonBarClasses is now an array, with each element a class that isn't `bar`

    alert("The non-bar class was: " + nonBarClasses.join("-")); 
});