gulp-watch only runs once

Question

Gulp watch runs only once on the first change. I am running Wordpress on apache2 on ubuntu 14 and am using a tutorial. It illustrates how to use gulp to watch for changes. It works okay for the first change - refreshes the browser which is http://localhost:3000. I'm pretty much new to setting up gulp watch so I am at a loss as to why it only runs once. The gulpfile.js is as follows. If anyone needs anything else to clarify please get back. Thanks

I have done the coding version of turning it off and on again. I have looked through various responses for this type of issue on stackoverflow and other places.

var gulp = require('gulp'),
   settings = require('./settings'),
   webpack = require('webpack'),
   browserSync = require('browser-sync').create(),
   postcss = require('gulp-postcss'),
   rgba = require('postcss-hexrgba'),
   autoprefixer = require('autoprefixer'),
   cssvars = require('postcss-simple-vars'),
   nested = require('postcss-nested'),
   cssImport = require('postcss-import'),
   mixins = require('postcss-mixins'),
   colorFunctions = require('postcss-color-function');

gulp.task('styles', function() {
  return gulp.src(settings.themeLocation + 'css/style.css')
    .pipe(postcss([cssImport, mixins, cssvars, nested, rgba, colorFunctions, autoprefixer]))
    .on('error', (error) => console.log(error.toString()))
    .pipe(gulp.dest(settings.themeLocation));
});

gulp.task('scripts', function(callback) {
  webpack(require('./webpack.config.js'), function(err, stats) {
    if (err) {
      console.log(err.toString());
    }

    console.log(stats.toString());
    callback();
  });
});

gulp.task('watch', function() {
 browserSync.init({
    notify: false,
    proxy: settings.urlToPreview,
    ghostMode: false
  });

  gulp.watch('./**/*.php', function() {
    browserSync.reload();
  });

  gulp.watch(settings.themeLocation + 'css/**/*.css', gulp.parallel('waitForStyles'));

  gulp.watch([settings.themeLocation + 'js/modules/*.js', settings.themeLocation + 'js/scripts.js'], 
       gulp.parallel('waitForScripts'));
});

gulp.task('waitForStyles', gulp.series('styles', function() {
  return gulp.src(settings.themeLocation + 'style.css')
    .pipe(browserSync.stream());
}))

gulp.task('waitForScripts', gulp.series('scripts', function(cb) {
  browserSync.reload();
  cb()
}))

I expect the browser view and functionality to be updated with every change of code. This only happens once after starting gulp with 'gulp watch'.

Try adding a "callback" function in your 'watch' task just like you did with the 'scripts' task and see if that helps. — Mark, Jan 08 '19 at 05:03
I think I'll add it as an answer - a task running only once is usually because gulp doesn't know it has finished the first time. — Mark, Jan 09 '19 at 07:47

Mark · Answer 1 · 2019-01-09T08:22:10.257

A gulp task that will only run once usually indicates that gulp is unable to determine that it has finished the first time and so gulp will not run it again.

Change to this code:

// notice the "done" added below
gulp.task('watch', function(done) {
 browserSync.init({
    notify: false,
    proxy: settings.urlToPreview,
    ghostMode: false
  });

  //  I also added a callback function below, just within this one gulp.watch
  gulp.watch('./**/*.php', function(done) {
    browserSync.reload();
    done();
  });

  gulp.watch(settings.themeLocation + 'css/**/*.css', gulp.parallel('waitForStyles'));
  gulp.watch([settings.themeLocation + 'js/modules/*.js', settings.themeLocation + 'js/scripts.js'], 
             gulp.parallel('waitForScripts'));
  done();
});

I have also seen it suggested to use this form of watch statement:

gulp.watch('src/pages/**/*.html').on('change',gulp.series(pages, browser.reload));

instead of the commonly used:

gulp.watch('src/pages/**/*.html', gulp.series(pages, browserSync.reload));

So if the callback solution didn't work, try using the suggested form of watch.

Any update on this? If the answer works please accept it so others who come here know that too. Thanks. — Mark, Jan 22 '19 at 00:23

score 0 · Answer 2 · answered Jun 05 '19 at 18:59

Under the rules for stackoverflow, my reputation is too low to tell you that Mark's answer worked for me under the comments to his answer, so I'll add it here. We added gulp to the Udemy course I'm taking and this has been a stumbling block for many users on that site.

Someone else will have to mark it as a correct answer. Probably gulp.js should be modified to take this use case into account, but this is my first time using it. Thanks Mark.

score 0 · Answer 3 · answered Feb 13 '20 at 09:44

Hello everyone i am in the same situation. I am running Wordpress on mamp pro. the answer from mark work for the html change but i stil get stop for Css en JS

If somebody can helping it wil be great tx.

My gulpfiles is:

 var gulp = require('gulp'),
settings = require('./settings'),
webpack = require('webpack'),
browserSync = require('browser-sync').create(),
postcss = require('gulp-postcss'),
rgba = require('postcss-hexrgba'),
autoprefixer = require('autoprefixer'),
cssvars = require('postcss-simple-vars'),
nested = require('postcss-nested'),
cssImport = require('postcss-import'),
mixins = require('postcss-mixins'),
colorFunctions = require('postcss-color-function');

gulp.task('styles', function() {
  return gulp.src(settings.themeLocation + 'css/style.css')
    .pipe(postcss([cssImport, mixins, cssvars, nested, rgba, colorFunctions, autoprefixer]))
    .on('error', (error) => console.log(error.toString()))
    .pipe(gulp.dest(settings.themeLocation));
});

gulp.task('scripts', function(callback) {
  webpack(require('./webpack.config.js'), function(err, stats) {
    if (err) {
      console.log(err.toString());
    }

    console.log(stats.toString());
    callback();
  });
});

gulp.task('watch', function(done) {
  browserSync.init({
    notify: false,
    proxy: settings.urlToPreview,
    ghostMode: false
  });

  gulp.watch('./**/*.php', function(done) {
    browserSync.reload();
    done();
  });
  gulp.watch(settings.themeLocation + 'css/**/*.css', gulp.parallel('waitForStyles'));
  gulp.watch([settings.themeLocation + 'js/modules/*.js', settings.themeLocation + 'js/scripts.js'], gulp.parallel('waitForScripts'));
});

gulp.task('waitForStyles', gulp.series('styles', function() {
  return gulp.src(settings.themeLocation + 'style.css')
    .pipe(browserSync.stream());
}))

gulp.task('waitForScripts', gulp.series('scripts', function(cb) {
  browserSync.reload();
  cb()
}))

gulp-watch only runs once

3 Answers3