⚡ A flexible dev server for Elm. Live reload included.
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A flexible dev server for Elm
Live reload included!





# Globally for a user:
npm install --global elm elm-live

# …or locally for a project:
npm install --save-dev elm elm-live

If you are using Elm 0.18

# Globally for a user:
npm install --global elm elm-live@prev

# …or locally for a project:
npm install --save-dev elm elm-live@prev

If you’d rather bring your own global elm, npm install --global elm-live will do.

Note that you need node 6.0+ to run the tool natively. But if you’re stuck on an older version, don’t worry! Rumour has it that you can transpile the code to ES5!



elm-live [...<options>] [--] ...<elm make args>  
elm-live --help



First, we spawn elm make with the elm make args you’ve given.

When the build is ready, we start a static HTTP server in the current directory. We inject a live reload snippet into every HTML file we serve. Every time a static file has changed, we’ll reload your app in all browsers you’ve opened it with. (Mobile and IE included!)

We also watch all *.elm files in the current directory and its subdirectories. Whenever you change, add or remove one of them, we’ll rebuild your program and reload the page.



-p, --port [PORT]

Set the port to start the server at. If the port is taken, we’ll use the next available one. PORT should be a valid port number. Default: 8000.

-e, --path-to-elm [PATH]

An absolute or relative path to elm. If you’ve installed elm-platform locally with npm (npm install --save-dev elm), you’ll likely want to set this to node_modules/.bin/elm. Default: elm.

-h, --host [HOSTNAME|IP]

Set the host interface to attach the server to. Default: localhost.

-S, --ssl

Start an https server instead of http. Defaults to false.

-d, --dir=PATH

The base for static content. Default: ..

-o, --open

We’ll open the app in your default browser as soon as the server is up.

-r, --no-recover

When elm make encounters a compile error, we keep elm-live running and give you time to fix your code. Pass --no-recover if you want the server to exit immediately whenever it encounters a compile error.

-u, --pushstate

Serve index.html on 404 errors. This lets us use client-side routing in Elm. For instance, we can have a URL like http://localhost:8000/account get handled by the Elm navigation package instead of failing with a 404 error.

-s, --start-page [STARTPAGE]

A custom html file to serve other than the default index.html.

-x, --proxyPrefix [PREFIX]

Proxy requests to paths starting with prefix to another server. Requires --proxyHost and should be a string like /api. Defaults to not proxying

-y, --proxyHost

Proxy requests to another server running at host. Requires --proxyPrefix and should be a full URL, eg. http://localhost:9000. Defaults to not proxying

-b, --before-build [EXECUTABLE]

Run EXECUTABLE before every rebuild. This way you can easily use other tools like elm-css or browserify in your workflow.

Heads up! At the moment, we only allow running a single executable without parameters. If you need more than that, please give us a shout at https://git.io/elm-live.before-build-args.

-a, --after-build [EXECUTABLE]

Just like --before-build, but runs after elm make.


You’re looking at it.



Have the compiler generate your index.html for you.

This command will start the server at http://localhost:8000 and compile your elm code to an index.html file in the folder you are running the command from. Note: the --open flag will open the page in the browser for you.

$ elm-live src/Main.elm --open

Use a custom HTML file

This command tells elm make to compile your elm code to a file named elm.js in the folder you are running the command from. From there you just need to include the script in default file of index.html as shown in the Elm guide here: https://guide.elm-lang.org/interop/

$ elm-live src/Main.elm --open -- --output=elm.js

To specify an HTML file other than the default, you can use the --start-page flag. This is an easy way to avoid elm make accidentally overriding your custom HTML.

$ elm-live src/Main.elm --open --start-page=custom.html -- --output=elm.js

Support client-side routing in Elm

This command tells the server to always serve up the index.html no matter what the URL is. This allows Elm to handle the routing clientside. Note: this option is a must when you are using Browser.Navigation

$ elm-live src/Main.elm --open --pushstate

Adding the debugger during dev

All possible elm make flags are available in elm-live. You just need to make sure they are passed after -- in the command. So the command below shows how to turn on the debugger in elm make.

elm-live src/Main.elm --open -- --debug



I’m seeing a SyntaxError about block-scoped declarations

If you’re seeing one of these:

SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode

make sure you’re running on node 6+. If you can’t upgrade, consider transpiling source/elm-live.js to ES5.

By the way, yarn should be warning you about installing incompatible packages. To get the same behavior in npm, set the engine-strict flag.


Original Author

Huge shoutout to the creator Tomek Wiszniewski!

Current Owner

Will King


Many thanks to Evan Czaplicki, the creator of Elm, for the Elm Compiler – the most brilliant language compiler the world has ever seen! Without elm make, elm-live would be a car without an engine.

Many thanks to Matt DesLauriers for the wonderful budo. That’s what does the heavy lifting on the static server side.

Warm thanks to our amazing contributors! Credits to Brian for making Windows support possible, Kurt for allowing a configurable --host and Josh for his work on enabling client-side navigation. Thanks to Ryan batch updates are nice and fast. Kudos to Mathieu, Rémy and Nicolas for making the developer experience smoother and to Gabriel for the --before-build option. Many thanks to Noah for making sure elm-live works smoothly with elm-test. Thanks to Darren for finding and fixing the bug with --port options on the 3.0.0 release.



MIT © Will King & Tomek Wiszniewski