How to clear the canvas for redrawing

Question

After experimenting with composite operations and drawing images on the canvas I\'m now trying to remove images and compositing. How do I do this?

I need to clear th

Answer 1

context.clearRect(0,0,w,h)   

fill the given rectangle with RGBA values :
0 0 0 0 : with Chrome
0 0 0 255 : with FF & Safari

But

context.clearRect(0,0,w,h);    
context.fillStyle = 'rgba(0,0,0,1)';  
context.fillRect(0,0,w,h);  

let the rectangle filled with
0 0 0 255
no matter the browser !