invalid now and tween.now values on animate step callback

[danielocdh]

I was a bit surprised I couldn't find the issue anywhere, sample here:
https://jsfiddle.net/apcso9gw/

[Ryan Neufeld]

Seems legit.

[Mx Corey Frang]

step is called before the property set hook is called.

https://github.com/jquery/jquery/blob/dbc4608ed10bd1347649e6f1514f459957cda003/src/effects/Tween.js#L37-L43

Try using progress instead which is called after, and guarnteed to be once per element per frame instead of once per property per element per frame, though since

jquery-color/jquery.color.js

Lines 620 to 627 in 889d029

 jQuery.fx.step[ hook ] = function( fx ) { 
 	if ( !fx.colorInit ) { 
 		fx.start = color( fx.elem, hook ); 
 		fx.end = color( fx.end ); 
 		fx.colorInit = true; 
 	} 
 	jQuery.cssHooks[ hook ].set( fx.elem, fx.start.transition( fx.end, fx.pos ) ); 
 }; 

doesn't update the tween.now it will still be this invalid thing.

We could update the tween.now or possibly use a custom tween in newer versions of jQuery - this hasn't been updated since jQuery 1.8 put in the new tween hooks.