Add babel-plugin-unpkg-rewrite package

packages/babel-plugin-unpkg-rewrite/modules/index.js

@@ -0,0 +1,36 @@
+const unpkg = require("unpkg")
+const warning = require("warning")
+
+function unpkgRewrite(dependencies = {}) {
+  return {
+    inherits: require("babel-plugin-syntax-export-extensions"),
+
+    visitor: {
+      "ImportDeclaration|ExportNamedDeclaration|ExportAllDeclaration"(path) {
+        if (!path.node.source) return // probably a variable declaration
+
+        const id = path.node.source.value
+
+        if (unpkg.isRemoteModuleIdentifier(id)) {
+          return // leave it alone
+        } else if (unpkg.isLocalModuleIdentifier(id)) {
+          path.node.source.value = `${id}?module`
+        } else if (unpkg.isBareModuleIdentifier(id)) {
+          const { packageName, file } = unpkg.parseBareModuleIdentifier(id)
+
+          warning(
+            dependencies[packageName],
+            'Missing version info for package "%s" in dependencies; falling back to "latest"',
+            packageName
+          )
+
+          const version = dependencies[packageName] || "latest"
+
+          path.node.source.value = `https://unpkg.com/${packageName}@${version}${file}?module`
+        }
+      }
+    }
+  }
+}
+
+module.exports = unpkgRewrite