instant – transparent live-reloading

Instant is ultra lightweight live-reload implementation with a unique feature set:

• Works in all browsers including mobile devices and IE6
• No browser plugin required
• Can be used as drop-in replacement for the express.static() middleware
• Production mode with zero overhead
• Automatic client code injection

How it works

All static files that are served by the middleware are added to a watch list. Whenever one of these files is modified the client gets notified an reloads the resource. CSS files are updated without reloading the whole page.

Instant automatically injects a script-tag right before the closing body tag of any HTML page (including dynamic ones) in order to load the client code.

The client uses server-sent events to listen for updates. Browsers that don't support EventSource will fall back to a hidden iframe.

Usage

var express = require('express');
var instant = require('instant');

var app = express();
app.use(instant(__dirname + '/static'));

If $NODE_ENV is set to production or { bypass: true } is passed as option, instant will behave just like express.static() with no additional overhead.

Reloading dynamic files

The instant middlware also exposes a .reload() function that can be called to reload arbitrary URLs. This can be useful if you want to reload scripts or stylesheets that have been processed/compiled on the fly.

Note: If you don't want to server any static files at all you can safely omit the root argument.

var express = require('express');
var instant = require('instant');

var app = express();
var ins = instant();

app.use(ins);

app.get('/tick', function(req, res) {
  res.send('Current date: ' + new Date());
});

// Trigger a reload of the page every 10 seconds:
setInterval(function() {
  ins.reload('/tick');
}, 10000);

Options

The following options are supported:

• bypass If set to true instant will behave just like express.static(). Defaults to process.env.NODE_ENV == 'production'
• watch List of file extensions to watch. Defaults to ['html', 'js', 'css']
• prefix A prefix to add to the URLs under which the client script and the EventSource are exposed. Defaults to '/instant'
• delay Amount of time in milliseconds to wait before triggering a reload. Defaults to 10

All other options like etag, dotfiles, index, etc. are passed on to send.

instant(1)

There is also an instant binary that can be used to spawn a development server in the current directory. The instant-server is packaged as speparate module and can be installed via npm:

npm install -g instant-server

The MIT License (MIT)

Copyright (c) 2013-2015 Felix Gnass

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.