Remote Javascript Scripting

Remote scripting is a way to interact with the server, rather that have to refresh the complete page to fetch new data.

For example, RSLite is a simple javascript object that allows to call the server with a certain string and get a response string back. The request is done using a image and the return value is passed using a cookie which is polled.

Remote javascript include:
Useful javascript "libraries" usually come in a separate .js file, that can be included into the html using <script type="text/javascript" language="JavaScript" src="foo.js" />. This is generally used to factorize the code out of the html or a bookmarklet.

The problem with bookmarklets is that IE 6 restricts bookmark urls to 500 characters.
But if all your bookmarklet does is dynamically insert a <script src="http://remoteserver.com/foo.js"> tag in the page, you can avoid this limitation by having most of the code in the remote .js file.

Here are some examples of use of this technique: Jon Udell's quote bookmarklet, Simon Willison's page weight (page weight bookmarklet) and some simple text processing bookmarklets.

Remote scripting via script include:
Remote script includes can be used as another way to interact with the server to achieve remote scripting.
For example, the dChat online chat and my port of dChat to C# will add new script tags dynamically to the DOM to call server-side functions (with a certain calling convention). The server returns javascript that ensures the DOM is cleaned after the call succeeds and can pass some additional return values in the form of client-side javascript calls.

I've also seen this used in a weird way before: you can have the server output the response javascript slowly while keeping the connection open. mod_pubsub uses this trick to delivery updates to various types of clients (flash, javascript,...).

Related:
RSLite's author, Brent Ashley, also wrote the JSRS (Javascript Remote Scripting) library.

Mozilla bug 18843 (dynamically added script not executable).

An explanation of server push via multipart mime-type content.
A server push framework in Java, based on javascript and maintaining the connection open to a servlet (pushlet).

OpenThought framework (javascript and iframes).

A project using client-side JavaScript to remotely invoke methods in ASP.NET pages.

I didn't actually write the page-weight bookmarklet. However, I did recently write a bookmarklet tutorial for SitePoint which describes the external-script include technique in additional detail: http://www.sitepoint.com/article/bookmarklets

Hi,

Can't seem to access your RSLite thing - where's it gone?!

Thanks.
Auf

Auf,
The link had changed. Instead of http://ashleyit.com/rs/rslite/ it's now http://www.ashleyit.com/rs/rslite/
I fixed the link in my post.

Don't forget Google is your friend ;-)