diff -r d3220b78c21a -r d382dacfd73f rt/mojo/src/main/java/org/apidesign/bck2brwsr/mojo/Java2JavaScript.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rt/mojo/src/main/java/org/apidesign/bck2brwsr/mojo/Java2JavaScript.java	Tue Feb 26 16:54:16 2013 +0100
@@ -0,0 +1,122 @@
+/**
+ * Back 2 Browser Bytecode Translator
+ * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. Look for COPYING file in the top folder.
+ * If not, see http://opensource.org/licenses/GPL-2.0.
+ */
+package org.apidesign.bck2brwsr.mojo;
+
+import org.apache.maven.plugin.AbstractMojo;
+
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import org.apache.maven.artifact.Artifact;
+import org.apache.maven.plugin.MojoExecutionException;
+import org.apache.maven.plugins.annotations.LifecyclePhase;
+import org.apache.maven.plugins.annotations.Mojo;
+import org.apache.maven.plugins.annotations.Parameter;
+import org.apache.maven.project.MavenProject;
+import org.apidesign.vm4brwsr.Bck2Brwsr;
+
+/** Compiles classes into JavaScript. */
+@Mojo(name="j2js", defaultPhase=LifecyclePhase.PROCESS_CLASSES)
+public class Java2JavaScript extends AbstractMojo {
+    public Java2JavaScript() {
+    }
+    /** Root of the class files */
+    @Parameter(defaultValue="${project.build.directory}/classes")
+    private File classes;
+    /** File to generate. Defaults bootjava.js in the first non-empty 
+     package under the classes directory */
+    @Parameter
+    private File javascript;
+    
+    @Parameter(defaultValue="${project}")
+    private MavenProject prj;
+    
+    
+
+    @Override
+    public void execute() throws MojoExecutionException {
+        if (!classes.isDirectory()) {
+            throw new MojoExecutionException("Can't find " + classes);
+        }
+
+        if (javascript == null) {
+            javascript = new File(findNonEmptyFolder(classes), "bootjava.js");
+        }
+
+        List<String> arr = new ArrayList<String>();
+        long newest = collectAllClasses("", classes, arr);
+        
+        if (javascript.lastModified() > newest) {
+            return;
+        }
+
+        try {
+            URLClassLoader url = buildClassLoader(classes, prj.getDependencyArtifacts());
+            FileWriter w = new FileWriter(javascript);
+            Bck2Brwsr.generate(w, url, arr.toArray(new String[0]));
+            w.close();
+        } catch (IOException ex) {
+            throw new MojoExecutionException("Can't compile", ex);
+        }
+    }
+
+    private static File findNonEmptyFolder(File dir) throws MojoExecutionException {
+        if (!dir.isDirectory()) {
+            throw new MojoExecutionException("Not a directory " + dir);
+        }
+        File[] arr = dir.listFiles();
+        if (arr.length == 1 && arr[0].isDirectory()) {
+            return findNonEmptyFolder(arr[0]);
+        }
+        return dir;
+    }
+
+    private static long collectAllClasses(String prefix, File toCheck, List<String> arr) {
+        File[] files = toCheck.listFiles();
+        if (files != null) {
+            long newest = 0L;
+            for (File f : files) {
+                long lastModified = collectAllClasses(prefix + f.getName() + "/", f, arr);
+                if (newest < lastModified) {
+                    newest = lastModified;
+                }
+            }
+            return newest;
+        } else if (toCheck.getName().endsWith(".class")) {
+            arr.add(prefix.substring(0, prefix.length() - 7));
+            return toCheck.lastModified();
+        } else {
+            return 0L;
+        }
+    }
+
+    private static URLClassLoader buildClassLoader(File root, Collection<Artifact> deps) throws MalformedURLException {
+        List<URL> arr = new ArrayList<URL>();
+        arr.add(root.toURI().toURL());
+        for (Artifact a : deps) {
+            arr.add(a.getFile().toURI().toURL());
+        }
+        return new URLClassLoader(arr.toArray(new URL[0]), Java2JavaScript.class.getClassLoader());
+    }
+}