Introduction to automating your tasks with the gulp.js build tool

What is Gulp?

Gulp.js is a streaming build system built on Node.js. This basically means that it can be configured to perform repetitive tasks and coding operations automatically during development. For example it can compile all your coffee scr
ipt whenever your file changes, or it can minify your CSS, or maybe synchronize all your development browsers and constantly refresh them on file change. 

Gulp uses a variety of plugins to do these tasks, and there is a plugin to do pretty much everything you'd need to do very easily. If you can't find one to do a particular operation, you can make your own ;)

Why do I need to use a build system?

For all modern web applications (hybrid apps, sites, web backends...) there are certain tasks that are almost essential to ensure high quality. For example checking your JavaScript for errors, minifying it, concatenating it. There are also certain tasks that just make developing easier, like having your your app tested in every browser and screen size whenever your file changes or monitoring file sizes and network requests.

It is true that it is possible to do most of these tasks without a build system or tool in place, but using something like Gulp or Grunt is much more efficient, easy to use, fast and keeps development code to a minimum and all in one place. 


Example Gulpfile for a typical Node.js Express app

I've created a Gulpfile for a typical Node Express project that uses coffee script and Less. It is just intended as a working example of how you can integrate everything together, so you can modify it to meet your specific project needs.


Setting up example project

  1. Open the console and navigate into a new working directory
  2. Run the command: git clone https://github.com/Lissy93/gulp-example.git
  3. Install the dependencies by running: npm install
  4. Start the gulp script bu running: gulp
So what the above steps should have done is: download the example project from GitHub, install all it's dependenceies found in the package.json and put them in the node_modules folder. Running gulp will then call the default task inside the gulpfile.js

What this project does

If you look in the gulpfile.js you'll see there's a whole load of tasks that are being covered. Mainly around processing the CSS and JavaScript ready for production. You can view the full list of tasks in the readme.md for the Git repo.

Testing it out

So once you've run the above commands in the terminal, if everything worked as it should have done your web browser should have opened. If it didn't try visiting http://localhost:4000. (If there is nothing, then check the console for errors.)

Browser Sync

If you open another browser and view the same URL you'll notice that the two browsers are in sync. So if you scroll down on one, the other will scroll, if you click a link on one all browsers will follow. This is really really useful testing your app out on a range of browsers and screen sizes all at once without having to even do any clicking, works better if you have a decent number of monitors ;) 
It's done using a gulp plugin called browser-sync.

Nodemon

Secondly you'll notice if you make any changes to any of the jade templates or views it will update live, across all your browsers as you code. No refreshing needed :) (you do need to set your IDE to autosave on keyup though, which should be default if your using any half decent ide). This is done using nodemon in gulp.

Linting, Compiling, Concatinating, Piping.... styles and scripts

Now for the coolest part, in your working directory open up the sources folder. If you edit any of the CSS, Less, JavaScript, CoffeeScript files you'll see that as it saves it creates a new version of the production code in your public directory, and refreshes the browsers accordingly. The code in the public directory is all minified and had everything else done to it to make it awesome and really efficient. Check the console for a list of all the tasks gulp has just done.

Exercises

  1. Try creating and modifying the JavaScript and CoffeeScript files in the javascript source directory, then look in the public directry and see what they're looking like in production form.
  2. In a similar way modify the CSS and Less file, you should see the changes in the browser
  3. Have a read through gulpfile.js and modify the configuration to suit your project, then test it out.
  4. Install a new gulp-plugin and set it up by seeing how the rest have been done
  5. Try running some of the tasks individually, for example gulp clean should just clean the public directory and gulp-watch should just watch for changes and update files accordingly.
If the console freezes, cancel the process (Ctrl+C) and rerun gulp.

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