feat: Add SVG sprite support (#319)

bin/build-sprite-string.js

@@ -0,0 +1,30 @@
+import defaultAttrs from '../src/default-attrs.json';
+
+const svgStartTag = `<svg xmlns="${defaultAttrs.xmlns}">\n<defs>\n`;
+const svgEndTag = '</defs>\n</svg>';
+
+/**
+ * Renders the inner sprites as SVG Symbols
+ * @param {object} icons the icons object
+ * @returns {string} the rendered string with SVG symbols
+ */
+function buildSpriteString(icons) {
+  const symbols = Object.keys(icons)
+    .map(icon => toSvgSymbol(icon, icons[icon]))
+    .join('');
+
+  return svgStartTag + symbols + svgEndTag;
+}
+
+/**
+ * Renders a SVG symbol tag
+ * @param {string} name The name of the icon
+ * @param {string} contents The contents of the icon
+ * @returns {string} the rendered SVG symbol
+ */
+function toSvgSymbol(name, contents) {
+  return `<symbol id="${name}" viewBox="${defaultAttrs.viewBox}">
+${contents}\n</symbol>\n`;
+}
+
+export default buildSpriteString;