Test case to show choppiness resulting from not using RAF timestamp

Velocity uses (new Date).getTime() instead of the RAF timestamp argument (velocity.js:3366):

/* We ignore RAF's high resolution timestamp since it can be significantly offset
   when the browser is
   under high stress; we opt for choppiness over allowing the browser to drop huge
   chunks of frames. */
var timeCurrent = (new Date).getTime();

I created a test case to demonstrate the resulting choppiness: http://codepen.io/joliss/pen/rLOxBb

My hope is that you can use this test case as a debugging aid, and as a motivating example to convince browser vendors to get the timestamp offset issues resolved.

Running the CodePen, we see that there is some slight choppiness with the default getTime implementation:

Using the RAF timestamp argument instead, the animation feels smoother, and the graph is perfectly smooth as well:

I thought that perhaps using the microsecond-resolution performance.now() function would improve smoothness, but it doesn’t seem to help much:

[Rycochet]

Btw, thank you @joliss for that awesome codepen and letting us know - Velocity wants performance and quality 😃

[Rycochet]

This is no longer an option in V2 - we always care about performance, and shim it if it doesn’t exist!