SVG and canvas aren't really interchangeable technologies. SVG is a type of retained mode graphics where everything is drawn from a rather abstract model (the SVG document). Canvas on the other hand is a kind of immediate mode graphics, where there is no model and the client (JavaScript) must take care of redrawing, animations etc.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…