Would it be possible to rotate sprite image from under such javascript browser environment (I mean get image.png from local disk or remote server, rotate it right by 5 degree, put the result to the screen at 100,100) ?2D canvas is probably the most advanced 2D non-GPU rendering API I've ever seen, even moreso than what Allegro pre-5 had. It's freaking overkill, at that. The only real problem is how good are browsers regarding its performance.
TNX for the answers,
Could you say yet to me, what part (of which standard, which technology) this canvas-api is ? Is it part of html is it part of javascript ? Is there something like an official standard/reference to that? (I know that i probably would find it in google, but im slightly overworked and would like to take oportunity for ease of direct answer) 
Yet to be concluding and claryfying: I understand I just need a web browser (i am using opera the most) and a text editor and my own set of sprites/images (in some directory at my local hard disk drive) and do not need even a internet connection Just to write run and test the javascript game in my browser ?
