This seems to work in most browsers:
function copyStylesInline(destinationNode, sourceNode) { var containerElements = ["svg","g"]; for (var cd = 0; cd < destinationNode.childNodes.length; cd++) { var child = destinationNode.childNodes[cd]; if (containerElements.indexOf(child.tagName) != -1) { copyStylesInline(child, sourceNode.childNodes[cd]); continue; } var style = sourceNode.childNodes[cd].currentStyle || window.getComputedStyle(sourceNode.childNodes[cd]); if (style == "undefined" || style == null) continue; for (var st = 0; st < style.length; st++){ child.style.setProperty(style[st], style.getPropertyValue(style[st])); } }}function triggerDownload (imgURI, fileName) { var evt = new MouseEvent("click", { view: window, bubbles: false, cancelable: true }); var a = document.createElement("a"); a.setAttribute("download", fileName); a.setAttribute("href", imgURI); a.setAttribute("target", '_blank'); a.dispatchEvent(evt);}function downloadSvg(svg, fileName) { var copy = svg.cloneNode(true); copyStylesInline(copy, svg); var canvas = document.createElement("canvas"); var bbox = svg.getBBox(); canvas.width = bbox.width; canvas.height = bbox.height; var ctx = canvas.getContext("2d"); ctx.clearRect(0, 0, bbox.width, bbox.height); var data = (new XMLSerializer()).serializeToString(copy); var DOMURL = window.URL || window.webkitURL || window; var img = new Image(); var svgBlob = new Blob([data], {type: "image/svg+xml;charset=utf-8"}); var url = DOMURL.createObjectURL(svgBlob); img.onload = function () { ctx.drawImage(img, 0, 0); DOMURL.revokeObjectURL(url); if (typeof navigator !== "undefined"&& navigator.msSaveOrOpenBlob) { var blob = canvas.msToBlob(); navigator.msSaveOrOpenBlob(blob, fileName); } else { var imgURI = canvas .toDataURL("image/png") .replace("image/png", "image/octet-stream"); triggerDownload(imgURI, fileName); } document.removeChild(canvas); }; img.src = url;}