Erasing previously drawn lines on an HTML5 canvas

Question

To play around with HTML5 canvas, I decided to make an app which draws an analogue clockface. Everything\'s fine, except that old lines don\'t get erased in the way that I w

Answer 1

For reasons that I could expand upon, you should consider clearing your canvas and redrawing it entirely unless there are performance or compositing reasons not to.

You want clearRect, something like this:

//clear the canvas so we can draw a fresh clock
ctx.clearRect(0, 0, canvasWidth, canvasHeight);

//redraw your clock here
/* ... */