Working loading of plugin

packages/gitbook-plugin/src/compile.js

@@ -0,0 +1,39 @@
+const fs = require('fs');
+const Promise = require('q');
+const browserify = require('browserify');
+const babelify = require('babelify');
+
+/**
+ * Compile a plugin to work with "gitbook-core" in the browser.
+ * @param {String} inputFile
+ * @param {String} outputFile
+ * @return {Promise}
+ */
+function compilePlugin(inputFile, outputFile) {
+    const d = Promise.defer();
+    const b = browserify({
+        standalone: 'GitBookPlugin'
+    });
+
+    b.add(inputFile);
+    b.external('react');
+    b.external('react-dom');
+    b.external('gitbook-core');
+    b.transform(babelify, {
+        presets: [
+            require('babel-preset-es2015'),
+            require('babel-preset-react')
+        ]
+    });
+
+    const output = fs.createWriteStream(outputFile);
+
+    b.bundle()
+    .pipe(output)
+    .on('error', (err) => d.reject(err))
+    .on('end', () => d.resolve());
+
+    return d.promise;
+}
+
+module.exports = compilePlugin;