Prepare.js

An easy method for executing JavaScript on the server in a browser-like environment, or more fancily, a basic framework for isomorphic JavaScript applications.

Prepare can preprocess HTML files with the extension ''.js.html'', executing JS snippets along the way. To specify the content of a script tag should be executed by Prepare, give it a ''type'' attribute of (or similar to) "server", such as:

<script type="server">console.log('Hi!');</script>
<script type="on/server">
    var db = require('../db');
    $('post').text(db.get(request.split('/').pop()));
</script>

These are then executed in a browser-like environment. In addition to all standard node-functionality, the following is currently also available:

• DOM implementation courtesy of jsdom
• A request- and response-object
• A few other useful small things, see the source for specifics

After parsing the whole document, Prepare removes all server-side code, adds a few useful definitions for the client side, and returns the resulting HTML. Client side script tags (lacking the "server" attribute) will not be executed by Prepare. To specify a script should be executed on both client and server, use a type of "client/server". Inside of these scripts, you can distinguish between the two via the onServer and onClient attributes. Note that all of the code inside these scripts will still be transmitted to the client, so make sure that it doesn't contain any sensitive information.

Another way to construct your pages is by using ''.html.js'' files. These are JavaScript files that are executed in a similar environment, but let you start with a blank slate. ''window.document'' is an empty document, so you can build your document in anyway you want. Here's an example of a script that serves a .js.html file indirectly:

response.hold();
require('fs').readFile('someFile.js.html', 'utf8', function(err, html) {
    document.write(html);
    response.release();
});

This is (apart from having a different request/response object and being slower) equivalent to visiting the .js.html file directly. By default, at the end of the script, the current document is sent to the client. You also have full access to the response object though, so you can decide to send something else entirely and close the connection yourself using response.end(). If you need it to wait before sending the response, you can use the hold() function to keep it from sending until you've called release() (you can hold/release more than once). Note that all code runs inside a fiber using ''fibrous'', so you could also rewrite the script above as:

var fs = require('fs'),
    html = fs.sync.readFile('someFile.js.html', 'utf8');
document.write(html);

If you only care about not blocking the event loop for other requests, this lets you keep your code structure simple while still being able to serve multiple requests simultaneously.

Planned additions:

• An easy way to use client/server modules
• Express-like additions to the request object (maybe even further integration?)
• Ease of use (installation and basic usage should be as simple as possible, to make it worth using :P)

Known bugs:

• Client-side script tags arenot executed, but if they have a (remote) src attibute, the file is still loaded (this slows down response time considerably).