if you are trying to cleat your canvas, but you have lines, you need to begin path again. So first try this
context.clearRect(0, 0, context.canvas.width, context.canvas.height);
context.beginPath();
== if that doesnt work, try
context.clearRect(0, 0, canvas.width, canvas.height);
context.beginPath();
== and if you had ROTATED OR SCALED YOUR CANVAS, you need to
ctx.save();
ctx.beginPath();
// Use the identity matrix while clearing the canvas
ctx.setTransform(1, 0, 0, 1, 0, 0);
ctx.clearRect(0, 0, myCanvas.width, myCanvas.height);
// Restore the transform
ctx.restore();//myCanvas.width=myCanvas.width
=== and lastly, if that doenst work, you can hack it by...
context.width=context.width
