Gulps gulp.watch not triggered for new or deleted files?

Question

The following Gulpjs task works fine when editing files in the glob match:

// watch task.
gulp.task('watch', ['build'], function () {
    gulp.watch(src + '/js/**/*.js', ['scripts']);
    gulp.watch(src + '/img//**/*.{jpg,jpeg,png,gif}', ['copy:images']);
    gulp.watch(src + '/less/*.less', ['styles']);
    gulp.watch(src + '/templates/**/*.{swig,json}', ['html']);
});

// build task.
gulp.task('build', ['clean'], function() {
    return gulp.start('copy', 'scripts', 'less', 'htmlmin');
});

However it doesn't work (it's not triggered) for new or deleted files. Is there something I'm missing?

EDIT: even using grunt-watch plugin it seems not working:

gulp.task('scripts', function() {
    return streamqueue(
        { objectMode: true },
        gulp.src([
            vendor + '/jquery/dist/jquery.min.js',
            vendor + '/bootstrap/dist/js/bootstrap.min.js'
        ]),
        gulp.src([
            src + '/js/**/*.js'
        ]).pipe(plugins.uglify())
    )
    .pipe(plugins.concat(pkg.name + '.min.js'))
    .pipe(gulp.dest(dest + '/js/'));
});

gulp.task('watch', ['build'], function () {
    plugins.watch({glob: src + '/js/**/*.js'}, function () {
        gulp.start('scripts');
    });
});

EDIT: Solved, it was this issue. Globs starting with ./ (that was the value of src) seems not working ATM.

Answer 1

Edit: Apparently gulp.watch does work with new or deleted files now. It did not when the question was asked.

The rest of my answer still stands: gulp-watch is usually a better solution because it lets you perform specific actions only on the files that have been modified, while gulp.watch only lets you run complete tasks. For a project of a reasonable size, this will quickly become too slow to be useful.

---

You aren't missing anything. gulp.watch does not work with new or deleted files. It's a simple solution designed for simple projects.

To get file watching that can look for new files, use the gulp-watch plugin, which is much more powerful. Usage looks like this:

var watch = require('gulp-watch');

// in a task
watch({glob: <<glob or array of globs>> })
        .pipe( << add per-file tasks here>> );

// if you'd rather rerun the whole task, you can do this:
watch({glob: <<glob or array of globs>>}, function() {
    gulp.start( <<task name>> );
});

Personally, I recommend the first option. This allows for much faster, per-file processes. It works great during development with livereload as long as you aren't concatenating any files.

You can wrap up your streams either using my lazypipe library, or simply using a function and stream-combiner like this:

var combine = require('stream-combiner');

function scriptsPipeline() {
    return combine(coffeeescript(), uglify(), gulp.dest('/path/to/dest'));
}

watch({glob: 'src/scripts/**/*.js' })
        .pipe(scriptsPipeline());

---

UPDATE October 15, 2014

As pointed out by @pkyeck below, apparently the 1.0 release of gulp-watch changed the format slightly, so the above examples should now be:

var watch = require('gulp-watch');

// in a task
watch(<<glob or array of globs>>)
        .pipe( << add per-file tasks here>> );

// if you'd rather rerun the whole task, you can do this:
watch(<<glob or array of globs>>, function() {
    gulp.start( <<task name>> );
});

and

var combine = require('stream-combiner');

function scriptsPipeline() {
    return combine(coffeeescript(), uglify(), gulp.dest('/path/to/dest'));
}

watch('src/scripts/**/*.js')
        .pipe(scriptsPipeline());