SVG to Base64 PNG

svg_to_png.js

function svg_to_png(svg, callback) {
  var svgData = (new XMLSerializer()).serializeToString(svg);

  var canvas = document.createElement("canvas");
  var svgSize = svg.getBoundingClientRect();
  canvas.width = svgSize.width;
  canvas.height = svgSize.height;
  var ctx = canvas.getContext("2d");

  var img = document.createElement("img");
  img.setAttribute("src", "data:image/svg+xml;base64," + btoa(unescape(encodeURIComponent(svgData))) );

  img.onload = function() {
    ctx.drawImage(img, 0, 0);
    callback(canvas.toDataURL("image/png"))
  };
}

// Usage
svg_to_png(document.getElementById("svg"), console.log)

https://jsfiddle.net/gc6znybd/