SRR: Serve Reload Replace

simple http server with built-in live reload, server-sent events, server side includes, and more!

Features

• Serve: Simple HTTP Server for static files
  • forced cache busting through Cache-Control: no-store headers
• Reload: Automatically watches for file changes, and reloads pages
  • uses light weight Server Sent Events to notify browser with file changes
  • automatically injects watcher client
  • customize the client behavior with your own client script
• Replace: Supports Server Side Includes directives

Install

$ npm install --global serve-reload-replace

Usage

$ srr --help

Usage: srr [options]
  --root     Path to serve & watch                                 default: $PWD
  --client   Path to custom EventSource client                     default: built-in
  --address  Specify network interface to use                      default: 0.0.0.0
  --port     Specify a port to use                                 default: 8080
  --index    Specify which file should be used as the index page   default: index.html
  --verbose  Verbose logging                                       default: false
  --help     Display Help

quick start

$ cd ~/project
$ srr

[02:02:46 PM] • Listening on 0.0.0.0 8080
[02:02:47 PM] • Watching files in /home/ahmad/project/

This will launch the server in the current working director and start watching local files for changes.

open a browser window and navigate to http://localhost:8080/ to start browsing.

The built-in EventSource client will automatically reload all pages whenever any file changes

NOTE: Future plans include selectively reloading resources in the browser.

with optional arguments & custom client

$ srr --root=~/projects/website/ --address=127.0.0.1 --port=2000 --client=js/my-client.js

[02:02:46 PM] • Listening on 127.0.0.1 2000
[02:02:47 PM] • Watching files in /home/ahmad/projects/website/

create a new file named my-client.js under ~/projects/website/js/

// connect to Server Sent Events special route
const sse = new EventSource(`${window.location.origin}/__events`);

sse.addEventListener("unlink", console.log);
sse.addEventListener("add", console.log);
sse.addEventListener("change", console.log);
sse.addEventListener("error", (event) => console.error("SSE error"));

NOTE: see Server Sent Events for more details.

open a browser window and navigate to http://127.0.0.1:2000/

[02:05:25 PM] • GET / ↦  200 OK
[02:05:25 PM] • SSE Client Connected: 1604257525819

with the server running, and your browser connected, edit / update / delete any file under your project folder and your client JS will receive events, while the server logs will show the events and the file path:

[02:10:15 PM] • change index.html
[02:11:30 PM] • add foo.html
[02:11:42 PM] • unlink foo.html

Server Sent Events

File system events are forwarded from Chokidar using Server Sent Events.

The built-in client is automatically served from the /__client endpoint, and it connects to the special path /__events which serves the events.

The built-in client simply listens to all event and executes a page reload through window.location.reload()

TODO:

• Track actively opened files, and only notify relevant client sessions
• Investigate using window.performance.getEntriesByType('resource') API to target specific elements per page / session (e.g. images / css)

Writing a custom SSE client

While the default behavior of the built-in client focuses on reloading the page content, you can replace it with your own client logic, simply point to the client path using --client argument.

Note: --client must be relative path to --root

client code

const sse = new EventSource(`${window.location.origin}/__events`);

sse.addEventListener("all", console.log);

See Using server-sent events article by Mozilla for more examples on what you can do.

Available events

add, addDir, change, unlink, unlinkDir, all

Note: for more details check out Chokidar's docs

Server Side Includes

The server will automatically process SSI directives:

Supported Directives

directive	parameters	example	description
echo	var	<!--#echo var="NODE_ENV" -->	displays the value of the specified environment variable
set	var, value	<!--#set var="foo" value="bar" -->	sets the value of an environment variable
printenv	space	<!--#printenv space=" " -->	outputs a list of all environment variables as JSON

API

You can use the serve-reload-replace programmatically as well:

const SRR = require('serve-reload-replace')

const instance = new SRR({
  verbose = false,
  root = process.cwd(),
  index = 'index.html',
  client
})

instance.start({
  address: '0.0.0.0',
  port: 8080
})

instance.stop()

See CLI Usage for available options.

Docker

Run as a docker image:

$ docker run -it -p 8080:8080 -v $(pwd)/www:/www ahmadnassri/serve-reload-replace

pass arguments and match the port and volume mount

$ docker run -it -p 3000:3000 -v /path/to/your/project:/my-project ahmadnassri/serve-reload-replace --port=3000 --root=/my-project

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Author: Ahmad Nassri • Twitter: @AhmadNassri