gulp + react + browserify

gulpfile.js

var gulp = require('gulp');
var browserify = require('browserify');
var source = require('vinyl-source-stream');
var reactify = require('reactify');

gulp.task('build', function(){
    var bundler = browserify('./app/app.js');
    bundler.transform(reactify, {"es6": true});
    return bundler.bundle()
                  .pipe(source("app.js"))
                  .pipe(gulp.dest("./js/"));
});

gulp.task('watch', function(){
    gulp.watch('app/**/*.js', ['build']);
});

gulp.task('default', ['build'])

package.json

{
  "name": "react",
  "version": "0.0.0",
  "description": "",
  "main": "gulpfile.js",
  "dependencies": {},
  "devDependencies": {
    "browserify": "^5.0.3",
    "gulp": "^3.8.6",
    "gulp-file-include": "^0.4.0",
    "reactify": "^0.14.0",
    "vinyl-source-stream": "^0.1.1"
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}