JSFiddle - React, Tailwind, and code Playground

HTML

<div mfour="testController">asd</div>

JavaScript

function testController() {
        alert('123');
    }

    $(function() {
        $('[mfour]').each(function(e, t) {
            var a = $(t).attr('mfour');
            console.log($.isFunction(testController));
            console.log($.isFunction(a));
        })
    });