feat(index): add asset resolving (HTML URLs) support (options.url)

src/lib/plugins/url.js

@@ -0,0 +1,74 @@
+/* eslint-disable */
+// External URL (Protocol URL)
+const TEST_URL = /^\w+:\/\//;
+// TODO(michael-ciniawsky)
+// extend with custom matchers
+// e.g <custom-element custom-src="">
+// (`options.url.filter`) (#159)
+const MATCH_ATTRS = [
+  { attrs: { src: true } },
+  { attrs: { href: true } },
+  { attrs: { srcset: true } }
+];
+
+// TODO(michael-ciniawsky)
+// add filter method for urls (e.g `options.url.filter`) (#158)
+const filter = (url, options) => {
+  return TEST_URL.test(url) || url.startsWith('//');
+}
+
+export default function (options = {}) {
+  return function (tree) {
+    let idx = 0;
+    const urls = {};
+
+    tree.match(MATCH_ATTRS, (node) => {
+      // <tag src="path/to/file.ext">
+      if (node.attrs.src) {
+        // Ignore <import>/<include
+        if (node.tag === 'import' || node.tag === 'include') return node;
+        // Ignore external && filtered urls
+        if (filter(node.attrs.src, options)) return node;
+        // Add url to messages.urls
+        urls[`HTML__URL__${idx}`] = node.attrs.src;
+        // Add content placeholders to HTML
+        node.attrs.src = '${' + `HTML__URL__${idx}` + '}';
+
+        idx++;
+
+        return node;
+      }
+      // <tag href="path/to/file.ext">
+      if (node.attrs.href) {
+        // Ignore external && filtered urls
+        if (filter(node.attrs.href, options)) return node;
+        // Add url to messages.urls
+        urls[`HTML__URL__${idx}`] = node.attrs.href;
+        // Add content placeholder to HTML
+        node.attrs.href = '${' + `HTML__URL__${idx}` + '}';
+
+        idx++;
+
+        return node;
+      }
+      // <tag srcset="path/to/file.ext">
+      if (node.attrs.srcset) {
+        // Ignore external && filtered urls
+        if (filter(node.attrs.srcset, options)) return node;
+        // Add url to messages.urls
+        urls[`HTML__URL__${idx}`] = node.attrs.srcset;
+        // Add content placeholder to HTML
+        node.attrs.srcset = '${' + `HTML__URL__${idx}` + '}';
+
+        idx++;
+
+        return node;
+      }
+    });
+
+    // Add urls to result.messages
+    tree.messages.push(urls);
+
+    return tree;
+  };
+}