HTML5 Canvas, shadowColor & shadowBlur

Question

My question is regarding this shadowBlur feature used on the 2nd (outer) rectangle below. The shadowBlur feature is applied to every shape after this rectangle. (If

Answer 1

Use either this:

ctx.save();
  ctx.shadowColor="black";
  ctx.shadowBlur = 10;       
  ctx.strokeRect(45,45,210,110); 
ctx.restore();

Or this:

ctx.shadowColor="black";
ctx.shadowBlur = 10;       
ctx.strokeRect(45,45,210,110); 
ctx.shadowColor= undefined; 
ctx.shadowBlur = undefined;       

I am not sure about 'undefined' in second case - something to nullify/reset the value.