An Introduction to PUG

Pug (formerly known as Jade) is a preprocessor which simplifies the task of writing . It also adds a ton of functionality, such as objects, conditionals, loops, mixins and templates. The syntax is arguably a lot cleaner to read and it can be a real time-saver when working with a lot of HTML (especially frameworks such as Bootstrap, Foundation, etc). HTML Javascript Lets take a peek at some Pug syntax & compare it to regular HTML.. // index.pug

doctype html html(lang='en') head title Pug demo body h1 Welcome to Pug Life div.container p I'm a p that needs to be contained! Note the use of indentation to nest our HTML as we require. And the lack of closing tags! And here’s the standard HTML output: // index.html Pug demo Welcome to Pug Life I'm a p that needs to be contained!

By comparison our pug code is much more concise. Additionally, the compiler will throw errors if we have any mistakes in our code – which makes for convenient error prevention. So let’s get started! How to install Pug Note: You’ll need NodeJS installed! Go ahead and if you haven’t already. install To install pug run the following command from your terminal: npm install -g pug-cli We install globally with as we’ll need access to Pug commands from terminal. -g Now in our root directory, create a file called . index.pug Lets test this out! Add the following text to our file as follows: // file: index.pug doctype html And lets compile it to HTML with the following command: pug index.pug We should now see our generated in the root directory. It will of course convert to HTML as follows: index.html // file: index.html When working on a larger project, you might want to use a more specific compile command, such as: pug -w ./ -o ./html -P The flag will watch our pug file for changes and re-compile automatically each time we save. will watch everything in the current directory. - will set the output folder to html. will make our HTML source code pretty printed, with indentation, line-breaks, etc. -w ./ o ./html -P Note: Once you’ve executed this command, keep your terminal running to continue the auto-compile! The Basics Lets get started on a basic HTML structure. Type up the following in your . index.pug doctype htmlhtmlheadbodyh1#title Lets get pugging!p I'm a paragraphp.I'm a multi-line paragraph!And this is the second line.p.para.This paragraph has class!.firstDiv A div with a class.#secondDiv A div with an id. Note the use of indentation! Make sure you tab your child elements. When you save and open up You’ll see the complete HTML generated like so.. index.html. Lets get pugging! I'm a paragraph

I'm a multi-line paragraph!And this is the second line.

This paragraph has class!

A div with a class. A div with an id. Attributes Lets take a look some syntax for setting attributes in pug. doctype htmlhtmlhead//- Invisible comment.//Visible comment. script(src="script.js") link(rel='stylesheet', href='css/main.css') bodya(href="https://google.com") google.com img(src="https://google.com/logo.png" alt="google logo")

input(type="password" name ="inputpass") input(type='checkbox' checked) input(type='checkbox' checked=true) input(type='checkbox' checked=false)

//Inline styles a(href="your-link", style={color: "Red", "font-size": "24px"}) I'm a link! Our HTML will generate as follows: google.com

I'm a link! Adding JavaScript One of the most powerful features of Pug, is the ability to easily make our HTML dynamic, using inline JavaScript. Lets take a look at a few examples: Variables - let name = 'Timothy'- let city = 'Montreal'- let transport = { type: 'Bike' }- let food = ['Tacos', 'Pizza', 'Cheetos'] // Incrementation for numeric variablesage++ // Assigning variables to elements p= name span.age= age Interpolation - let size ="medium"img(src=`https://google.com/logo-${size}.png` alt="logo") ---------------------// output: Loops ul city in ['Sydney', 'Montreal', 'New York']li= city each ul city, index in ['Sydney', 'Montreal', 'New York']li= 'Number ' + index + ': ' + city each -------------------------------------------------// output: Sydney Montreal New York Number 0: Sydney Number 1: Montreal Number 2: New York Conditionals if user h2 Welcome back #{user}!else if admin h2 Hey #{admin}!else h2 Sign up! Mixins // Declaration listulli Sydneyli Montrealli New York mixin // Use_+_list_+_list ------------------// output: Sydney Montreal New York Sydney Montreal New York Mixins compile as functions, and therefore can take arguments! mixin city(name)li.city= nameul+city('Sydney')+city('Montreal')+city('New York') --------------------// output: Sydney Montreal New York The features we’ve looked at here are really just the tip of the iceberg! For the full specs check out . PugJS.org — Getting Started Structuring your Pug files A well organized template system is a crucial part of any development process. What follows is a look at how we can organize our projects using both and . includes extends Includes Includes allow you to insert the contents of one Pug file into another. All you need to do is add an directive into your main pug file, as follows: include doctype htmlhtml bodyh1 My Headingp Here goes the text. additions.pug include Lets now create the file and add the following content: additions.pug headtitle My Sitescript(src='/js/jquery.js')script(src='/js/app.js') Our files will compile merged into like so: index.html My Site My Heading Here goes the text.

Extends The keyword allows a template to extend a layout or parent template. It can then override certain pre-defined blocks of content, using the command. extends block We want to keep our projects as organised as possible! A logical template system will define a base template, and then all the other templates extend from it. For example: // file: index.pug layout.pug extends contenth1 hello world! block Here we’ve set our file as the base template. With a call to the file via extends. index.pug layout.pug Note the use of the command. This is how we direct part of a template to be extended. block // file: layout.pug doctype htmlhtml(lang="en")headmeta(charset='utf-8')body contenth2 hello again world! block Here is the content of our layout.pug, we use the command with the same name (you can call it whatever you like!), so the pug engine knows where to put the code block. block This code will compile as follows: hello world! hello again world! Of course you can use as many blocks as you like, and create as many pug files as you like. The point is to build a logical structure into our projects & keep our code clean and organised! Conclusion And that’s it! We’ve setup a Pug development environment and covered the fundamentals. We’ve looked at many of the features provided by adding JavaScript such as variables, interpolation, loops, conditionals and mixins. We’ve also looked at how to structure our Pug files using templating with the include and extend directives. I hope you found this article useful! You can on Medium. I’m also on . Feel free to leave any questions in the comments below. I’ll be glad to help out! follow me Twitter