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livereload / livereload-js

LiveReload JavaScript code that communicates with the server and implements reloading
http://livereload.com/
MIT License
830 stars 190 forks source link

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LiveReload.js CI Status

What is LiveReload?

LiveReload is a tool for web developers and designers. See livereload.com for more info.

To use LiveReload, you need a client (this script) in your browser and a server running on your development machine.

This repository (livereload.js) implements the client side of the protocol. The client connects to a LiveReload server via web sockets and listens for incoming change notifications. When a CSS or an image file is modified, it is live-refreshed without reloading the page. When any other file is modified, the page is reloaded.

The server notifies the client whenever a change is made. Available servers are:

If you are a web developer looking to use LiveReload, you should refer to your LiveReload server/app/tool's documentation, rather that this repository. You should use the copy of livereload.js script bundled with your server, because it's guaranteed to be compatible, and may be customized for that server.

Most LiveReload server vendors will serve livereload.js on the LiveReload port. When your server is running, you can typically access the script at http://0.0.0.0:35729/livereload.js.

Please read on only if you are:

What is livereload.js?

This repository contains a JavaScript file implementing the client side of the LiveReload protocol. It gets change notifications from a LiveReload server and applies them to the browser.

If you are developing a LiveReload server, see dist/livereload.js for the latest version built using the sources in this repository. We require LiveReload server vendors to distribute livereload.js as part of their apps or tools.

An old version of this script is also bundled with the LiveReload browser extensions, but it's not getting updated and only serves for compatibility with very old clients.

Features:

Would love, but doesn't seem possible:

Installing using Bower

This script is published on Bower. (But, to reiterate: the preferred method is to avoid installing it altogether, and instead use the one bundled with your LiveReload server/app/tool.)

Installation:

bower install livereload-js --save-dev

This gives you a component containing a single script file, dist/livereload.js.

Installing using npm and Browserify

Including livereload.js into your Browserify bundle probably makes no sense, because livereload.js isn't something you would ship to production.

But if you insist and you know what you're doing, you can install LiveReload via npm:

npm install livereload-js --save

and then add this to your bundle:

window.LiveReloadOptions = { host: 'localhost' };
require('livereload-js');

Note that livereload-js package uses window and document globals, so won't run under Node.js environment.

The reason you need to specify LiveReloadOptions is that livereload.js won't be able to find its <script> tag and would normally bail out with an error message.

Using livereload.js

This script is meant to be included into the web pages you want to monitor, like this:

<script src="http://localhost:35729/livereload.js"></script>

LiveReload 2 server listens on port 35729 and serves livereload.js over HTTP (besides speaking the web socket protocol on the same port).

A slightly smarter way is to use the host name of the current page, assuming that it is being served from the same computer. This approach enables LiveReload when viewing the web page from other devices on the network:

<script>document.write('<script src="http://'
    + location.host.split(':')[0]
    + ':35729/livereload.js"></'
    + 'script>')</script>

However, since location.host is empty for file: URLs, we need to account for that:

<script>document.write('<script src="http://'
    + (location.host || 'localhost').split(':')[0]
    + ':35729/livereload.js"></'
    + 'script>')</script>

LiveReload.js finds a script tag that includes …/livereload.js and uses it to determine the hostname/port to connect to. It also understands some options from the query string: host, port, snipver, mindelay and maxdelay.

snipver specifies a version of the snippet, so that we can warn when the snippet needs to be updated. The currently recommended snipver is version 1:

<script>document.write('<script src="http://'
    + (location.host || 'localhost').split(':')[0]
    + ':35729/livereload.js?snipver=1"></'
    + 'script>')</script>

Additionally, you might want to specify mindelay and maxdelay, which is minimum and maximum reconnection delay in milliseconds (defaulting to 1000 and 60000).

Alternatively, instead of loading livereload.js from the LiveReload server, you might want to include it from a different URL. In this case, add a host parameter to override the host name. For example:

<script src="https://github.com/livereload/livereload-js/raw/master/dist/livereload.js?host=localhost"></script>

Options

Options can either be specified as query parameters of the <script src="https://github.com/livereload/livereload-js/raw/master/.../livereload.js"> tag's source URL, or as a global window.LiveReloadOptions dictionary. If the dictionary is specified, livereload.js does not even try looking for its <script> tag.

The set of supported options is the same for both methods:

Plugin order

By default LiveReload runs external plugins one by one, then tries live CSS reloading, live IMG reloading, reloads chrome extension and as a last resort reloads the whole page, if no plugin matched the updated file name. So, by default assume pluginOrder = ['external', 'css', 'img', 'extension', 'others'].

Alternatively, you can define pluginOrder to match your workflow.

If you're using LiveReloadOptions object on page, then define array of plugins:

var LiveReloadOptions = {
    ...,
    pluginOrder: ['css', 'img'],
    // or
    pluginOrder: 'css img'.split(' ')
}

If you're configuring LivReload using <script> tag, then use following syntax:

<script src="https://github.com/livereload/livereload-js/raw/master//livereload.js?pluginOrder=css,img">

This means LiveReload will only try to do live css and img reloading, regardless of any external plugins.

You can specify external plugins order by adding each plugin id into pluginOrder or just use external to run all external plugins in default order.

Issues & Limitations

Live reloading of imported stylesheets has a 200ms lag. Modifying a CSS @import rule to reference a not-yet-cached file causes WebKit to lose all document styles, so we have to apply a workaround that causes a lag.

Our workaround is to add a temporary <link /> element for the imported stylesheet we're trying to reload, wait 200ms to make sure WebKit loads the new file, then remove <link /> and recreate the @import rule. This prevents a flash of unstyled content. (We also wait 200 more milliseconds and recreate the @import rule again, in case those initial 200ms were not enough.)

Live image reloading is limited to <img src="https://github.com/livereload/livereload-js/raw/master/.." />, background-image and border-image styles. Any other places where images can be mentioned?

Live image reloading is limited to jpg, jpeg, gif, and png extensions. Maybe need to add svg there? Anything else?

Communicating with livereload.js

It is possible to communicate with a running LiveReload script using DOM events:

The LiveReload object is also exposed as window.LiveReload, with LiveReload.disconnect(), LiveReload.connect(), and LiveReload.shutDown() available. However, I'm not yet sure if I want to keep this API, so consider it non-contractual. (And please tell me if you have a use for it!)

Having trouble?

To enable debugging output to console, append ?LR-verbose to your URL.

Hacking on LiveReload.js

Requirements:

To install additional prerequisites:

npm install

To build:

npm run build

To run tests:

npm test

Manual testing: open files in test/html/* in various browsers, make some changes and make sure they are applied.

Testing the Browserify usage scenario: npm run test-manual, then perform manual testing of test/html/browserified/.

Releasing a new version

  1. Run npm version with the applicable identifier (major/minor/patch/...).

  2. Do some manual testing.

  3. Create a release on GitHub.

  4. Run npm publish.

License

livereload-js is available under the MIT license. See the LICENSE file for details.