Gulp Basics

Gulp can do a lot. This is just an overview of the basics. Once you understand this, then you can add more to Gulp on your own. The documentation for different packages I have used has been great and we also have a great community on FreeCodeCamp ready to help with any project.

What is Gulp?

Gulp is a JavaScript build/task runner. Are you using Jade, but need HTML? Sass, but need CSS? CoffeeScript, but need JavaScript? Or maybe you just want to concatenate and/or minify what you already have? Gulp can do all of this for you easily, so you do not have to keep going back to your terminal after every little change.

Why use Gulp?

We use a lot of CodePen on FreeCodeCamp. CodePen allows the use of preprocessors without having to do anything else. You can view the compiled version if a preprocessor was used. It looks a lot different. You can make a project in React on CodePen, choose Babel as the JavaScript preprocessor and everything will work. If you were to do this same project locally without processing everything, then you would not get what you expected. This is where Gulp comes in.

How do I use Gulp?

Again, this is just an overview of the basics. The overview is going to be processing Sass to CSS, concatenating and minifying stylesheets and scripts, and implementing Gulp watch. You need Node and NPM installed on your computer before doing anything though. You most likely have this already, but enter node -v and npm -v in your terminal to check.

• Change to the project directory and run npm init in the terminal.

  • This creates the package.json file in the working directory.
  • This would also be a good time to run touch .gitignore in the terminal and add node_modules/ to the file, so you will not be pushing all of those packages to GitHub.

• Run npm install --save-dev gulp gulp-concat gulp-minify-css gulp-rename gulp-sass gulp-uglify in the terminal. This may take a couple of minutes to finish.

  • This is installing 6 different node_modules. You can take a look at the package.json file and see all of these listed under devDependencies and at the node_modules folder and see every package you installed.
  • gulp-concat is for concatenating stylesheets and scripts, gulp-minify-css is for minifying CSS, gulp-rename is for renaming the file, gulp-sass is for Sass to CSS, and gulp-uglify is for minifying JS.

• Run touch gulpfile.js in the terminal.

  • You are now ready to start.

• You are going to need to require all of the files you just saved. You do this in gulpfile.js.

'use strict';

var gulp = require('gulp');
var concat = require('gulp-concat');
var minifyCss = require('gulp-minify-css');
var rename = require('gulp-rename');
var sass = require('gulp-sass');
var uglify = require('gulp-uglify');

• We need to start somewhere, so Sass to CSS first? Here we are going to process Sass to CSS, minify the CSS, and rename the file.
  • The name of the task sass (more on that later).
  • In the current directory we are looking for a folder named assets, then a folder named scss, then a file named main.scss.
  • We are processing the Sass to CSS and logging if an error occurs.
  • The CSS is then minified. This is just getting rid of all those extra lines and spaces. The computer does not need those to read the file and it drastically reduces the file size.
  • Since the file is now minified it makes sense to rename it .min.css.
  • The last step is saving the main.min.css file somewhere and it is going in the current directory to a folder named public, then a folder named css.

gulp.task('sass', function() {
    return gulp.src('./assets/scss/main.scss')
    .pipe(sass().on('error', sass.logError))
    .pipe(minifyCss({compatibility: 'ie8'}))
    .pipe(rename('main.min.css'))
    .pipe(gulp.dest('./public/css'));
});

• Now we can get a little more into Gulp and try concatenating and minifying all of the script files. What if you only have one script now, so you do not have anything to concatenate? Maybe get rid of some of the CDNs you have and make them scripts. But you will get to bigger projects that have several scripts.
  • Please note that I am not covering source maps. I think that is the next step after this basic overview, so look over that once you understand what you are doing here.
  • The current tasks are named concatScripts and minifyScripts.
  • This is the same basic structure as sass. All of the files are added to gulp.src, but we first have to save that concatenated file before it can be minified.
  • The JavaScript minifying is called uglify.
  • Do you notice ['concatScripts] after minifyScripts? That means concatScripts will actually run first every time we try to run minifyScripts.

gulp.task('concatScripts', function() {
    return gulp.src([
        './assets/js/script-1.js',
        './assets/js/script-2.js',
        './assets/js/script-3.js'
    ]))
    .pipe(concat('app.js'))
    .pipe(gulp.dest('./assets/js'));
});

gulp.task('minifyScripts', ['concatScripts'], function() {
    return gulp.src('assets/js/app.js')
    .pipe(uglify())
    .pipe(rename('app.min.js'))
    .pipe(gulp.dest('public/app/js'));
});

• You can now go to the terminal and type in gulp sass and/or gulp minifyScripts. This will run each one, but we want to make it easier on us. We are going to make a default build, so we can just enter gulp into the terminal. We are also going to add gulp watch, so whenever you save a file that is listed in the watch it will run what you have told it to run.
  • We made a task called build. This is very similar to minifyScripts since there is an array in it. Whenever we enter gulp build into the terminal it will run sass and minifyScripts (which actually runs concatScripts first).
  • We also made a task called watch. This is the time saver task. In the terminal you run gulp watch. Gulp will stay open on the terminal, so you probably want to run it in another tab. Whenever a file is updated and saved in the scss folder with a .scss extension the sass task will be run. And the same thing for a file in the js folder with a .js extension, but concatScripts and minifyScripts will run.
  • The last task is default. You can just run gulp in the terminal and it will run the default task. The default task here is calling the build task, which just runs all the tasks we have on the page.

gulp.task('build', ['sass', 'minifyScripts']);

gulp.task('watch', function() {
  gulp.watch('./assets/scss/**/*.scss', ['sass']);
    gulp.watch('./assets/js/**/*.js', ['minifyScripts']);
});

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

This is what your final gulpfile.js file should look like:

'use strict';

var gulp = require('gulp');
var concat = require('gulp-concat');
var minifyCss = require('gulp-minify-css');
var rename = require('gulp-rename');
var sass = require('gulp-sass');
var uglify = require('gulp-uglify');

gulp.task('sass', function() {
    return gulp.src('./assets/scss/main.scss')
    .pipe(sass().on('error', sass.logError))
    .pipe(minifyCss({compatibility: 'ie8'}))
    .pipe(rename('main.min.css'))
    .pipe(gulp.dest('./public/css'));
});

gulp.task('concatScripts', function() {
    return gulp.src([
        './assets/js/script-1.js',
        './assets/js/script-2.js',
        './assets/js/script-3.js'
    ]))
    .pipe(concat('app.js'))
    .pipe(gulp.dest('./assets/js'));
});

gulp.task('minifyScripts', ['concatScripts'], function() {
    return gulp.src('assets/js/app.js')
    .pipe(uglify())
    .pipe(rename('app.min.js'))
    .pipe(gulp.dest('public/app/js'));
});

gulp.task('build', ['sass', 'minifyScripts']);

gulp.task('watch', function() {
  gulp.watch('./assets/scss/**/*.scss', ['sass']);
    gulp.watch('./assets/js/**/*.js', ['minifyScripts']);
});

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