I am currently using canvg() and Canvas2Image to copy my SVG to a canvas and then convert the canvas to PNG. I would like to maintain the image format and not use PDF.
just to make @Lars Kotthoff's answer more concrete. "example of how to export a png directly from an svg" has a working example. the code snippet/gist tries to first apply all css to the svg inline and then draw the image on the canvas and export the data as png. (internally it adopted svg-crowbar code). and i apply the technique in my project and it works smoothly - a download button that can download the svg image rendered using nvd3.