export.js

function downloadImage(isSvg) {
			// Retrieve svg node
			const svgNode = attrs.svg.node();

			if (isSvg) {
				let source = serializeString(svgNode);
				//add xml declaration
				source = '<?xml version="1.0" standalone="no"?>\r\n' + source;
				//convert svg source to URI data scheme.
				var url = "data:image/svg+xml;charset=utf-8," + encodeURIComponent(source);
				saveAs(url, "graph.svg")
			} else {
				// Get image quality index (basically,  index you can zoom in)
				const quality = attrs.imageDownloadScale;
				// Create image
				const image = new Image;
				image.onload = () => {
					// Create image canvas
					const canvas = document.createElement('canvas')
					// Set width and height based on SVG node
					const rect = svgNode.getBoundingClientRect();
					canvas.width = rect.width * quality;
					canvas.height = rect.height * quality;

					// Draw background
					const context = canvas.getContext('2d')
					context.fillStyle = '#FAFAFA';
					context.fillRect(0, 0, rect.width * quality, rect.height * quality);
					context.drawImage(image, 0, 0, rect.width * quality, rect.height * quality);

					// Set some image metadata
					let dt = canvas.toDataURL('image/png');
					dt = dt.replace(/^data:image\/[^;]*/, 'data:application/octet-stream');
					dt = dt.replace(/^data:application\/octet-stream/, 'data:application/octet-stream;headers=Content-Disposition%3A%20attachment%3B%20filename=download.png');

					// Invoke saving function
					saveAs(dt, 'graph.png')
				};

				const blob = new Blob([serializeString(svgNode)], { type: "image/svg+xml" });
				// Set image source
				image.src = URL.createObjectURL(blob);
			}

			// This function invokes save window
			function saveAs(uri, filename) {
				// create link
				var link = document.createElement('a');
				if (typeof link.download === 'string') {
					document.body.appendChild(link); // Firefox requires the link to be in the body
					link.download = filename;
					link.href = uri;
					link.click();
					document.body.removeChild(link); // remove the link when done
				} else {
					location.replace(uri);
				}
			}

			// This function serializes SVG and sets all necessary attributes
			function serializeString(svg) {
				const xmlns = "http://www.w3.org/2000/xmlns/";
				const xlinkns = "http://www.w3.org/1999/xlink";
				const svgns = "http://www.w3.org/2000/svg";
				svg = svg.cloneNode(true);
				const fragment = window.location.href + "#";
				const walker: any = document.createTreeWalker(svg, NodeFilter.SHOW_ELEMENT, null, false);
				while (walker.nextNode()) {
					for (const attr of walker.currentNode.attributes) {
						if (attr.value.includes(fragment)) {
							attr.value = attr.value.replace(fragment, "#");
						}
					}
				}
				svg.setAttributeNS(xmlns, "xmlns", svgns);
				svg.setAttributeNS(xmlns, "xmlns:xlink", xlinkns);
				const serializer = new XMLSerializer;
				const string = serializer.serializeToString(svg);
				return string;
			};
		}