Super-simple Gulp task for Browserify (no fancy super-efficient watch here)

gulpfile.js

'use strict';

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

gulp.task('browserify', function () {
    return browserify('./js/src/app.js')
        .bundle()
        .pipe(source('compiled.js'))    // Pass desired output filename to vinyl-source-stream
        .pipe(gulp.dest('./js/dist'));  // dest takes output dir for compiled bundle
        // both lines are necessary :(
});

gulp.task('watch', function (){
    livereload.listen();
    gulp.watch(['path/to/js'], ['browserify']);
});

gulp.task('default', ['watch']);

You can use the Chrome Livereload plugin for minimal setup
https://chrome.google.com/webstore/detail/livereload/jnihajbhpnppcggbcgedagnkighmdlei?hl=en