wait for jquery on async load (or other class)

waitfor.js

function doSomething() {
    console.log('do something with jQuery');
}

var waitInterval = window.setInterval(function () {
    try {
        if (jQuery === 'function') {
            clearInterval(waitInterval);
            doSomething();
        }
    }
    catch
       (e) {
    }
}, 100);