How to add/remove class at start and end of tweenmax animation?

Question

JavaScript

How can I add the class as the animation started and remove the class when it ended.

var tl = new TimelineLite();
tl.from('#heroPreloader', 2, {onStart: onStart, onComplete: onComplete})
.from('#heroContent', 3, {autoAlpha: 0});

function onStart() {
  tl.set('#heroPreloader', {className: '+=preloader_show'});
}

function onComplete() {
  tl.set('#heroPreloader', {className: '-=preloader_show'})
}

For some reason, in the onStart and onComplete callbacks, the class is not added and removed at the start of the animation and the end of the animation. Although console.log is normally called from these functions.

Answer 1

The documentation says that the first argument to set() should be an object, not a string. Replace with $('#heroPreloader')