/elm-app-local-deps

Template project for elm apps using https://github.com/halfzebra/create-elm-app v1.1.2 as a local instead of a global dependency

Primary LanguageElm

This project is bootstrapped with Create Elm App.

Below you will find some information on how to perform basic tasks.
You can find the most recent version of this guide here.

Table of Contents

Sending feedback

You are very welcome with any feedback

Installing Elm packages

node elm package install <package-name>

Installing JavaScript packages

To use JavaScript packages from npm, you'll need to add a package.json, install the dependencies, and you're ready to go.

npm init -y # Add package.json
npm install --save-dev pouchdb-browser # Install library from npm
// Use in your JS code
import PouchDB from 'pouchdb-browser';
const db = new PouchDB('mydb');

Folder structure

my-app/
  .gitignore
  README.md
  elm-package.json
  src/
    App.elm
    favicon.ico
    index.html
    index.js
    main.css
  tests/
    elm-package.json
    Main.elm
    Tests.elm

For the project to build, these files must exist with exact filenames:

  • src/index.html is the page template;
  • src/favicon.ico is the icon you see in the browser tab;
  • src/index.js is the JavaScript entry point.

You can delete or rename the other files.

You may create subdirectories inside src.

Available scripts

In the project directory you can run:

node elm build

Builds the app for production to the build folder.

The build is minified, and the filenames include the hashes.
Your app is ready to be deployed!

node elm start

Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.

The page will reload if you make edits.
You will also see any lint errors in the console.

node elm test

Run tests with node-test-runner

You can make test runner watch project files by running:

node elm test --watch

node elm eject

Note: this is a one-way operation. Once you eject, you can’t go back!

If you aren’t satisfied with the build tool and configuration choices, you can eject at any time.

Instead, it will copy all the configuration files and the transitive dependencies (Webpack, Elm Platform, etc.) right into your project, so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point, you’re on your own.

You don’t have to use 'eject' The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However, we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.

node elm <elm-platform-comand>

Create Elm App does not rely on the global installation of Elm Platform, but you still can use it's local Elm Platform to access default command line tools:

package

Alias for elm-package

Use it for installing Elm packages from package.elm-lang.org

repl

Alias for elm-repl

make

Alias for elm-make

reactor

Alias for elm-reactor

Changing the Page <title>

You can find the source HTML file in the public folder of the generated project. You may edit the <title> tag in it to change the title from “Elm App” to anything else.

Note that normally you wouldn’t edit files in the public folder very often. For example, adding a stylesheet is done without touching the HTML.

If you need to dynamically update the page title based on the content, you can use the browser document.title API and ports.

Adding a Stylesheet

This project setup uses Webpack for handling all assets. Webpack offers a custom way of “extending” the concept of import beyond JavaScript. To express that a JavaScript file depends on a CSS file, you need to import the CSS from the JavaScript file:

main.css

body {
  padding: 20px;
}

index.js

import './main.css'; // Tell Webpack to pick-up the styles from base.css

In development, expressing dependencies this way allows your styles to be reloaded on the fly as you edit them. In production, all CSS files will be concatenated into a single minified .css file in the build output.

You can put all your CSS right into src/main.css. It would still be imported from src/index.js, but you could always remove that import if you later migrate to a different build tool.

Adding Images and Fonts

With Webpack, using static assets like images and fonts works similarly to CSS.

By requiring an image in JavaScript code, you tell Webpack to add a file to the build of your application. The variable will contain a unique path to the said file.

Here is an example:

import logoPath from './logo.svg'; // Tell Webpack this JS file uses this image
import { Main } from './Main.elm';

Main.embed(
    document.getElementById('root'),
    logoPath // Pass image path as a flag for Html.programWithFlags
  );

Later on, you can use the image path in your view for displaying it in the DOM.

view : Model -> Html Msg
view model =
    div []
        [ img [ src model.logo ] []
        , div [] [ text model.message ]
        ]

Using the public Folder

Changing the HTML

The public folder contains the HTML file so you can tweak it, for example, to set the page title. The <script> tag with the compiled code will be added to it automatically during the build process.

Adding Assets Outside of the Module System

You can also add other assets to the public folder.

Note that we normally encourage you to import assets in JavaScript files instead. For example, see the sections on adding a stylesheet and adding images and fonts. This mechanism provides a number of benefits:

  • Scripts and stylesheets get minified and bundled together to avoid extra network requests.
  • Missing files cause compilation errors instead of 404 errors for your users.
  • Result filenames include content hashes so you don’t need to worry about browsers caching their old versions.

However there is an escape hatch that you can use to add an asset outside of the module system.

If you put a file into the public folder, it will not be processed by Webpack. Instead it will be copied into the build folder untouched. To reference assets in the public folder, you need to use a special variable called PUBLIC_URL.

Inside index.html, you can use it like this:

<link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">

Only files inside the public folder will be accessible by %PUBLIC_URL% prefix. If you need to use a file from src or node_modules, you’ll have to copy it there to explicitly specify your intention to make this file a part of the build.

When you run npm run build, Create React App will substitute %PUBLIC_URL% with a correct absolute path so your project works even if you use client-side routing or host it at a non-root URL.

In Elm code, you can use %PUBLIC_URL% for similar purposes:

// Note: this is an escape hatch and should be used sparingly!
// Normally we recommend using `import`  and `Html.programWithFlags` for getting 
// asset URLs as described in “Adding Images and Fonts” above this section.
img [ src "%PUBLIC_PATH%/logo.svg" ] []

In JavaScript code, you can use process.env.PUBLIC_URL for similar purposes:

const logo = `<img src=${process.env.PUBLIC_URL + '/img/logo.svg'} />`;

Keep in mind the downsides of this approach:

  • None of the files in public folder get post-processed or minified.
  • Missing files will not be called at compilation time, and will cause 404 errors for your users.
  • Result filenames won’t include content hashes so you’ll need to add query arguments or rename them every time they change.

When to Use the public Folder

Normally we recommend importing stylesheets, images, and fonts from JavaScript. The public folder is useful as a workaround for a number of less common cases:

  • You need a file with a specific name in the build output, such as manifest.webmanifest.
  • You have thousands of images and need to dynamically reference their paths.
  • You want to include a small script like pace.js outside of the bundled code.
  • Some library may be incompatible with Webpack and you have no other option but to include it as a <script> tag.

Note that if you add a <script> that declares global variables, you also need to read the next section on using them.

Setting up API Proxy

To forward the API ( REST ) calls to backend server, add a proxy to the elm-package.json in the top level json object.

{
    ...
    "proxy" : "http://localhost:1313",
    ...
}

Make sure the XHR requests set the Content-type: application/json and Accept: application/json. The development server has heuristics, to handle it's own flow, which may interfere with proxying of other html and javascript content types.

 curl -X GET -H "Content-type: application/json" -H "Accept: application/json"  http://localhost:3000/api/list

Running Tests

Create Elm App uses elm-test as its test runner.

Dependencies in Tests

To use packages in tests, you also need to install them in tests directory.

node elm test --add-dependencies elm-package.json

Deployment

node elm build creates a build directory with a production build of your app. Set up your favourite HTTP server so that a visitor to your site is served index.html, and requests to static paths like /static/js/main.<hash>.js are served with the contents of the /static/js/main.<hash>.js file.

Static Server

For environments using Node, the easiest way to handle this would be to install serve and let it handle the rest:

npm install -g serve
serve -s build

The last command shown above will serve your static site on the port 5000. Like many of serve’s internal settings, the port can be adjusted using the -p or --port flags.

Run this command to get a full list of the options available:

serve -h

GitHub Pages

Note: this feature is available with react-scripts@0.2.0 and higher.

Step 1: Add homepage to package.json

The step below is important!
If you skip it, your app will not deploy correctly.

Open your package.json and add a homepage field:

  "homepage": "https://myusername.github.io/my-app",

Create React App uses the homepage field to determine the root URL in the built HTML file.

The predeploy script will run automatically before deploy is run.

Step 2: Deploy the site by running gh-pages -d build

Then run:

gh-pages -d build

Step 3: Ensure your project’s settings use gh-pages

Finally, make sure GitHub Pages option in your GitHub project settings is set to use the gh-pages branch:

gh-pages branch setting

Step 4: Optionally, configure the domain

You can configure a custom domain with GitHub Pages by adding a CNAME file to the public/ folder.

Notes on client-side routing

GitHub Pages doesn’t support routers that use the HTML5 pushState history API under the hood (for example, React Router using browserHistory). This is because when there is a fresh page load for a url like http://user.github.io/todomvc/todos/42, where /todos/42 is a frontend route, the GitHub Pages server returns 404 because it knows nothing of /todos/42. If you want to add a router to a project hosted on GitHub Pages, here are a couple of solutions:

  • You could switch from using HTML5 history API to routing with hashes. If you use React Router, you can switch to hashHistory for this effect, but the URL will be longer and more verbose (for example, http://user.github.io/todomvc/#/todos/42?_k=yknaj). Read more about different history implementations in React Router.
  • Alternatively, you can use a trick to teach GitHub Pages to handle 404 by redirecting to your index.html page with a special redirect parameter. You would need to add a 404.html file with the redirection code to the build folder before deploying your project, and you’ll need to add code handling the redirect parameter to index.html. You can find a detailed explanation of this technique in this guide.

IDE setup for Hot Module Replacement

Remember to disable safe write if you are using VIM or IntelliJ IDE, such as WebStorm.