Gulp Watch only run once - gulp

Question

I'm using this Gulp Watch sample: https://github.com/floatdrop/gulp-watch/blob/master/docs/readme.md#starting-tasks-on-events.
var gulp = require('gulp');
var watch = require('gulp-watch');
var batch = require('gulp-batch');
gulp.task('build', function () { console.log('Working!'); });
gulp.task('watch', function () {
watch('**/*.js', batch(function () {
gulp.start('build');
}));
});
When I run it on my Windows 8 machine, it only runs the first time I change a file:
C:\test>gulp watch
[08:40:21] Using gulpfile C:\test\gulpfile.js
[08:40:21] Starting 'watch'...
[08:40:21] Finished 'watch' after 2.69 ms
[08:40:31] Starting 'build'...
Working!
[08:40:31] Finished 'build' after 261 µs
Next time nothing happens. Why?

Answer 1

For me it was adding a "return" to the task:
gulp.task('styles', function(){
return gulp.src('css/styles.css')
.pipe(autoprefixer())
.pipe(gulp.dest('build'));
});

Answer 2

If you read the documentation closely, you see the following phrase:
You can pass plain callback, that will be called on every event or wrap it in gulp-batch to run it once
So, that's basically the deal with gulp-batch. To constantly watch it, just remove the batch call:
gulp.task('build', function (done) {
console.log('Working!');
done();
});
gulp.task('watch', function () {
watch('app/*.js', function () {
gulp.start('build');
});
});
(and add the 'done' callback to build to let Gulp know when you're finished).
Btw... I'm not sure, but I think gulp-watch is meant to not only watch files, but also directly returning a vinyl object. So actually using the built-in gulp.watch should have the same effect:
gulp.task('watch', function () {
gulp.watch('app/**/*.js', ['build']);
});

Answer 3

This appears to be known issue
I had the same problem and used the same as ddprrt. The difference was using directory glob (wildcard) as apposed to absolute path.
I changed this:
gulp.task('watch', function() {
gulp.watch('sass/shortcutcss/*.scss', ['sass'])
});
to this:
gulp.task('watch', function() {
gulp.watch('sass/**/*.scss', ['sass'])
});

Answer 4

This problem made me crazy for a weekend. I tried all:
Add done()-Event
Rename/Touch/Clear target CSS
Be more specific with the filepaths
But the (reason for this problem and) the solution was so easy that I felt pathetic after that:
Just update your nodejs installation, mine was 0.12.x! No wonder that this doesn't worked.
After that the watch event works again. Sometimes it goes wrong again, too. But in this cases just save your file a second time and it get recognized. (I think foundation/gulp watch checks for changes to fast and while your file get replaced with the new uploaded one)

Answer 5

Long story:
For me it did not work for long time. All seems to be set right but run only once.
But suddenly I started with parcel js on another project and same thing happened with their builtn watch. So I looked for the answer and I found out that problem was with my Vim settings.
Answer what helped me is this one from #acobster https://stackoverflow.com/a/55435197/2686510
In short:
Update .vimrc by adding set backupcopy=yes