sapper-template
The default Sapper template, available for Rollup and webpack.
Getting started
degit
Using degit
is a scaffolding tool that lets you create a directory from a branch in a repository. Use either the rollup
or webpack
branch in sapper-template
:
# for Rollup npx degit "sveltejs/sapper-template#rollup" my-app# for webpack npx degit "sveltejs/sapper-template#webpack" my-app
Using GitHub templates
Alternatively, you can use GitHub's template feature with the sapper-template-rollup or sapper-template-webpack repositories.
Running the project
However you get the code, you can install dependencies and run the project in development mode with:
cd my-appnpm install # or yarn npm run dev
Open up localhost:3000 and start clicking around.
Consult sapper.svelte.dev for help getting started.
Structure
Sapper expects to find two directories in the root of your project — src
and static
.
src
The src directory contains the entry points for your app — client.js
, server.js
and (optionally) a service-worker.js
— along with a template.html
file and a routes
directory.
src/routes
This is the heart of your Sapper app. There are two kinds of routes — pages, and server routes.
Pages are Svelte components written in .svelte
files. When a user first visits the application, they will be served a server-rendered version of the route in question, plus some JavaScript that 'hydrates' the page and initialises a client-side router. From that point forward, navigating to other pages is handled entirely on the client for a fast, app-like feel. (Sapper will preload and cache the code for these subsequent pages, so that navigation is instantaneous.)
Server routes are modules written in .js
files, that export functions corresponding to HTTP methods. Each function receives Express request
and response
objects as arguments, plus a next
function. This is useful for creating a JSON API, for example.
There are three simple rules for naming the files that define your routes:
- A file called
src/routes/about.svelte
corresponds to the/about
route. A file calledsrc/routes/blog/[slug].svelte
corresponds to the/blog/:slug
route, in which caseparams.slug
is available to the route - The file
src/routes/index.svelte
(orsrc/routes/index.js
) corresponds to the root of your app.src/routes/about/index.svelte
is treated the same assrc/routes/about.svelte
. - Files and directories with a leading underscore do not create routes. This allows you to colocate helper modules and components with the routes that depend on them — for example you could have a file called
src/routes/_helpers/datetime.js
and it would not create a/_helpers/datetime
route
static
The static directory contains any static assets that should be available. These are served using sirv.
In your service-worker.js file, you can import these as files
from the generated manifest...
;
...so that you can cache them (though you can choose not to, for example if you don't want to cache very large files).
Bundler config
Sapper uses Rollup or webpack to provide code-splitting and dynamic imports, as well as compiling your Svelte components. With webpack, it also provides hot module reloading. As long as you don't do anything daft, you can edit the configuration files to add whatever plugins you'd like.
Production mode and deployment
To start a production version of your app, run npm run build && npm start
. This will disable live reloading, and activate the appropriate bundler plugins.
You can deploy your application to any environment that supports Node 8 or above. As an example, to deploy to Now, run these commands:
npm install -g nownow
Using external components
When using Svelte components installed from npm, such as @sveltejs/svelte-virtual-list, Svelte needs the original component source (rather than any precompiled JavaScript that ships with the component). This allows the component to be rendered server-side, and also keeps your client-side app smaller.
Because of that, it's essential that the bundler doesn't treat the package as an external dependency. You can either modify the external
option under server
in rollup.config.js or the externals
option in webpack.config.js, or simply install the package to devDependencies
rather than dependencies
, which will cause it to get bundled (and therefore compiled) with your app:
npm install -D @sveltejs/svelte-virtual-list
Bugs and feedback
Sapper is in early development, and may have the odd rough edge here and there. Please be vocal over on the Sapper issue tracker.