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encore watch & Code Splitting

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Let's get Encore to build our assets! Do that by going back to the terminal and saying:

yarn watch

This reads our app.js file and outputs the final files into a public/build directory - you can see that here. Once it's done, it sits and watches for more changes. If we modify any files, it will rebuild the assets.

Let's try this! Find your browser and refresh! Woo! We have a gray background. That proves the CSS is being processed!

Seeing the Code Splitting

If you view the page source, you'll see one link tag for build/app.css and... cool! The JavaScript is already being split into three different files. The Twig function knows to render all of them. This is not something you really need to think or worry about - Webpack does this to help your users download the files faster and cache them better.

Moving our Styles

Before we keep going, let's move our real CSS - it's currently in public/styles/app.css - into the new app.css file that's being processed by Webpack. Open that up, copy everything inside, then delete the file entirely.

Now go to the new assets/styles/app.css, remove the gray background and paste!

144 lines | assets/styles/app.css
@import url('https://fonts.googleapis.com/css2?family=Montserrat:ital,wght@0,400;0,500;0,700;1,400;1,500;1,700&display=swap');
body {
font-family: 'Montserrat', sans-serif;
a, a:hover {
color: #000;
// ... lines 10 - 144

In base.html.twig, delete the link tag that pointed to the old static file.

Now... when we refresh, it still looks good! That's because, over at the terminal, Encore noticed that we changed the app.css file and automatically rebuilt things.

Installing Bootstrap CSS

While we're here, we also have a link tag that points to a Bootstrap CDN. That's okay, but we can now properly install bootstrap into our app. First, over at your terminal, open a new tab so that yarn watch can keep doing its thing in the background. Run:

yarn add 'bootstrap@^4.6' --dev

Two things. First, if you searched npmjs.com, you'd learn that the name of the package that gives you Bootstrap is... bootstrap! And second, that --dev flag isn't really important - it would be fine if you didn't include that.

This adds bootstrap to our package.json file and downloads it into the node_modules/ directory. Delete the old link tag... which temporarily will make our site look terrible.

Then go into app.css. On top, we can import this: import then ~bootstrap.

145 lines | assets/styles/app.css
@import '~bootstrap';
// ... lines 2 - 145

That's it. Webpack will magically load all the bootstrap CSS and include it in the final, built app.css file. The tilde is a magic character that tells Webpack to look for a package in the node_modules/ directory. This is a special syntax that you only use inside CSS files.

Let's check it! Refresh now and... all better! View the source again. Woh! Even the CSS is being split into two files. I normally don't even think about this, but I wanted you to see it.

Oh, and these really long ugly filenames? When you build Encore for production, those will be very simple names, usually a number - like 55.js. It won't expose all these path details.

Next let's figure out how and where stimulus is installed and build our very first stimulus controller!