HTML canvas stroke() Method
Draw a path, shaped as the letter L - in a red color:
Internet Explorer 9, Firefox, Opera, Chrome, and Safari support the stroke() method.
Note: Internet Explorer 8 and earlier versions, do not support the <canvas> element.
Definition and Usage
The stroke() method actually draws the path you have defined with all those moveTo() and lineTo() methods. The default color is black.
Tip: Use the strokeStyle property to draw with another color/gradient.
HTML Canvas Reference