gulpfile.js

/**
 * Automatically reload your node.js app on file change with Gulp
 * https://gist.github.com/webdesserts/5632955
 */
var gulp = require('gulp'),
    spawn = require('child_process').spawn,
    node;

/**
 * $ gulp server
 * description: launch the server. If there's a server already running, kill it.
 */
gulp.task('server', function() {
    if (node) node.kill();
    node = spawn('node', ['app.js'], {stdio: 'inherit'});
    node.on('close', function (code) {
        if (code === 8) {
            gulp.log('Error detected, waiting for changes...');
        }
    });
});

/**
 * $ gulp
 * description: start the development environment
 */
gulp.task('default', function() {
    gulp.run('server');

    gulp.watch(['**/*.js', '**/*.html', '!public/**/*.*'], function() {
        gulp.run('server');
    });
});

// clean up if an error goes unhandled.
process.on('exit', function() {
    if (node) node.kill();
});