Gulp Watch Not Watching File Changes

My gulp-watch task has been started normally, and the gulp command didn't exit too, every seems good. However, when I make changes to my files, I can't see the changes in my output

Solution 1:

I have solved this on my self. The problem is that I declared the done argument to my task handler, but I didn't call it. Because of this, the tasks won't finish, and the watch task will not work until all previous tasks will work. (I guess without referring to the documents).

---

With my gulpfile.js in the question, the gulp command line will looks like following:

cosmozhang:bowuguan $ gulp 
[13:44:36] Using gulpfile ~/work/cordova/bowuguan/gulpfile.js
[13:44:36] Starting 'sass'...
[13:44:36] Starting 'templates'...
[13:44:36] Starting 'scripts'...
[13:44:36] Starting 'watch'...
[13:44:36] Finished 'watch' after 16 ms
[13:44:36] Finished 'sass' after 801 ms

Look at the old gulpfile.js, the done callback was called in the sass task, but was not called in the templates and scripts task. So only the sass task was finished, and we cannot see the finish message of templates and scripts.

---

Now with my new gulpfile.js like this:

var gulp = require('gulp');
var gutil = require('gulp-util');
var bower = require('bower');
var concat = require('gulp-concat');
var sass = require('gulp-sass');
var minifyCss = require('gulp-minify-css');
var rename = require('gulp-rename');
var jade = require('gulp-jade');
var sh = require('shelljs');
var browserify = require('browserify');
var source = require('vinyl-source-stream');

var paths = {
  sass: ['./src/scss/**/*.scss'],
  jade: ['./src/jade/**/*.jade'],
  js: ['./src/js/**/*.js']
};

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

gulp.task('sass', function(done) {
  gulp.src('./src/scss/ionic.app.scss')
    .pipe(sass())
    .on('error', sass.logError)
    .pipe(gulp.dest('./www/css/'))
    .pipe(minifyCss({
      keepSpecialComments: 0
    }))
    .pipe(rename({ extname: '.min.css' }))
    .pipe(gulp.dest('./www/css/'))
    .on('end', done);
});

gulp.task('templates', function (done) {
  gulp.src('./src/jade/**/*.jade')
    .pipe(jade({
      pretty: true
    }))
    .pipe(gulp.dest('./www/'))
    .on('end', done);
});

gulp.task('scripts', function (done) {
  var bundleStream = browserify('./src/js/app.js').bundle();
  bundleStream
    .pipe(source('app.js'))
    .pipe(rename('app.js'))
    .pipe(gulp.dest('./www/js/'))
    .on('end', done);
});

gulp.task('watch', function() {
  gulp.watch(paths.sass, ['sass']);
  gulp.watch(paths.jade, ['templates']);
  gulp.watch('./src/js/app.js', ['scripts']);
});

gulp.task('install', ['git-check'], function() {
  return bower.commands.install()
    .on('log', function(data) {
      gutil.log('bower', gutil.colors.cyan(data.id), data.message);
    });
});

gulp.task('git-check', function(done) {
  if (!sh.which('git')) {
    console.log(
      '  ' + gutil.colors.red('Git is not installed.'),
      '\n  Git, the version control system, is required to download Ionic.',
      '\n  Download git here:', gutil.colors.cyan('http://git-scm.com/downloads') + '.',
      '\n  Once git is installed, run \'' + gutil.colors.cyan('gulp install') + '\' again.'
    );
    process.exit(1);
  }
  done();
});

This time the gulp command outputs this:

cosmozhang:bowuguan $ gulp 
[13:58:20] Using gulpfile ~/work/cordova/bowuguan/gulpfile.js
[13:58:20] Starting 'sass'...
[13:58:20] Starting 'templates'...
[13:58:20] Starting 'scripts'...
[13:58:20] Starting 'watch'...
[13:58:20] Finished 'watch' after 18 ms
[13:58:20] Finished 'templates' after 135 ms
[13:58:20] Finished 'scripts' after 170 ms
[13:58:21] Finished 'sass' after 778 ms
[13:58:21] Starting 'default'...
[13:58:21] Finished 'default' after 4.06 μs
[14:02:22] Starting 'templates'...
[14:02:22] Finished 'templates' after 75 ms

At 13:58:20, all the tasks were started. And all of them were finished in a second, as I called the done callback in all tasks. Then, on 14:02:22, I modified my index.jade file and the templates task started and finished immediately.

---

Conclusion:

1. If you encountered the problem that your gulp-watch task doesn't watch your changes with no outputs, you may check your command line outputs to ensure that all the previous tasks were finished. gulp-watch will not work until all the previous tasks were finished.

2. If a task doesn't finish as you expected, you can check your task handler funtion in gulpfile.js. Make sure that the function takes no argument. If it takes any argument, the first argument will be regarded as the callback function, and the task will not end until you call the callback. That means your task declaration should looks like one of the following 3 forms:

   No argument:

   gulp.task('templates', function () {  // takes no argument
       ...
   });
   

   With arguments:

   gulp.task('templates', function (done) {  // takes a argument
       ...
       done();  // call the callback
   });
   

   With arguments:

   gulp.task('templates', function (done) {  // takes a argument
       ...
       gulp
           ...
           .on('end', done);  // set the callback argument as gulp's end callback
   });