Javascript

Javascript is a client-side scripting language. Its main differences relative to server-sided languages is that it is run by the client machine instead of the server machine. This can be useful in order to unload the server machine. Combined with XML technology it forms the core-technology of the AJAX programming philosophy.

Replace html markup in html characters

Here's how to replace html markup in html characters

divtag.replace(/<([^<>]*)>/g,"&lt;$1&gt;")

Bookmarklets

Bookmarklets are little javascript one-liners that aim to compose a more or less complex url.

User scripts

User scripts are cool javascripts scripts that are injected ad-hoc in the desired web-pages by the browser. They allow to add extra functionalities that weren't previously thought by the web-page owners/designers.

Firefox (Greasemonkey)

User scripts for Firefox are also called greasmonkey scripts and they require the greasemonkey extension for firefox to be installed. They require to be named foo.user.js, otherwise firefox doesn't installs them. To install them, simply open the greasemonkey script from your firefox browser.

Sample

//#deliciousmp3.user.js
// ==UserScript==
// @name          del.icio.us mp3
// @namespace     
// @description   add del.icio.us mp3 player to links
// @include       http://*
// @exclude       http://*.icio.us/*
// ==/UserScript==
   var head,script
   head = document.getElementsByTagName('head')[0];
   if (!head) { return; }
   script = document.createElement('script');
   script.type = 'text/javascript';
   script.src = 'http://del.icio.us/js/playtagger'
   head.appendChild(script);

Opera (user scripts)

User scripts for Opera are similar to greasemonkey scripts. But they require to be named strictly foo.js. Thus, a greasemonkey script needs to have the user. removed from its name, in order to work in Opera. To install them simply copy them into the user scripts folder in your Opera profile folder.

Sample

Same script as for firefox, but with some slight modifications...

//#deliciousmp3.js
// ==UserScript==
// @name          del.icio.us mp3
// @namespace
// @description   add del.icio.us mp3 player to links
// @include       http://* 
// @exclude       http://*.icio.us/* 
// ==/UserScript==
  var head,script;
  head = document.getElementsByTagName('head')[0];
  if (head){
      script = document.createElement('script');
      script.type = 'text/javascript';
      script.src = 'http://del.icio.us/js/playtagger';
      head.appendChild(script);        
  }

Examples

Del.icio.us mp3 player user script

This one should work for Opera 9.X (save it as deliciousmp3.js).

// ==UserScript==
// @name          del.icio.us mp3
// @namespace
// @description   add del.icio.us mp3 player to links
// @include       http://* 
// @exclude       http://*.icio.us/* 
// ==/UserScript==
   var head,script;
   head = document.getElementsByTagName('head')[0];
   if (head){
       script = document.createElement('script');
       script.type = 'text/javascript';
       script.src = 'http://del.icio.us/js/playtagger'
       head.appendChild(script);        
   }

External References

• Javascript Wikipedia,
• Bookmarklet Wikipedia,
• Greasemonkey Wikipedia,
• Greasemonkey scripts largest repo.