let isTrue = false; document.getElementById("hamburger").onclick = function() {toggle()}; function stop() { let someElement= document.getElementById("wholeBody"); someElement.className += " stop";//add "newclass" to element (space in front is important) } function deleteStop() { let someElement= document.getElementById("wholeBody"); someElement.className -= " stop"; } function toggle() { isTrue = !isTrue; if (isTrue === true){ stop(); } if (isTrue === false) { deleteStop() } }