javascript SocialHistory Check whether the visitor has visited a certain site_javascript skills

window.onload = function() {
var sl = new SocialHistory();
alert(sl.doesVisit("www.jb51.net"));
}
If the user has ever used www.jb51.net, then this function will return true, otherwise it will return false.

In fact, the principle is not complicated. It uses the attributes of the link's a:visited pseudo-class. First generate an iframe on the page, and set a and a:visited to different styles in this iframe. Then insert the link to the website into the iframe. The browser will set the a:visited style for the visited links based on the user's access history. Finally, the final style of the link is obtained. If it is a:visited, it can be considered that the user has visited the website. For specific implementation methods, please refer to the source code.

This script is mainly used to display social bookmark icons, which can properly display the website used by the user. But I am worried that this approach is suspected of stealing user privacy? Although this method can only determine whether the user has visited a specific website, it cannot obtain all access history without limit.



/*

* Social Limit - Only the social you care about.

*

* Enables your site to know which social bookmarking badges to display to your

* visitors. It tells you all social sites the user has gone to, or you can

* query for a specific one.

*

* For example:

*

* var sl = SocialHistory();

* alert( sl.doesVisit("Digg") ); // Returns true/false, -1 if unknown.

* var listOfVisitedSites = sl.visitedSites();

* var checkedSites = sl.checkedSites();

*

* If you want to add more sites to check, you can pass that in as a dictionary

* to History:

*

* var more = { "Humanized": "http://humanized.com",

* "Azarask.in": ["http://azarask.in", "http://azarask.in/blog"]

* };

* var sl = SocialHistory(more);

* alert( sl.doesVisit("Humanized") );

*

* For a list of built-in sites, see the sites variable below.

*

* Copyright (c) 2008 Aza Raskin (http://azarask.in/blog)

*

* 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.

*

*/

var SocialHistory = function( moreSites ){

var sites = {

"Digg": ["http://digg.com", "http://digg.com/login"],

"Reddit": ["http://reddit.com", "http://reddit.com/new/", "http://reddit.com/controversial/", "http://reddit.com/top/", "http://reddit.com/r/reddit.com/", "http://reddit.com/r/programming/"],

"StumbleUpon": ["http://stumbleupon.com"],

"Yahoo Buzz": ["http://buzz.yahoo.com"],

"Facebook": ["http://facebook.com/home.php", "http://facebook.com", "https://login.facebook.com/login.php"],

"Del.icio.us": ["https://secure.del.icio.us/login", "http://del.icio.us/"],

"MySpace": ["http://www.myspace.com/"],

"Technorati": ["http://www.technorati.com"],

"Newsvine": ["https://www.newsvine.com", "https://www.newsvine.com/_tools/user/login"],

"Songza": ["http://songza.com"],

"Slashdot": ["http://slashdot.org/"],

"Ma.gnolia": ["http://ma.gnolia.com/"],

"Blinklist": ["http://www.blinklist.com"],

"Furl": ["http://furl.net", "http://furl.net/members/login"],

"Mister Wong": ["http://www.mister-wong.com"],

"Current": ["http://current.com", "http://current.com/login.html"],

"Menaeme": ["http://meneame.net", "http://meneame.net/login.php"],

"Oknotizie": ["http://oknotizie.alice.it", "http://oknotizie.alice.it/login.html.php"],

"Diigo": ["http://www.diigo.com/", "https://secure.diigo.com/sign-in"],

"Funp": ["http://funp.com", "http://funp.com/account/loginpage.php"],

"Blogmarks": ["http://blogmarks.net"],

"Yahoo Bookmarks": ["http://bookmarks.yahoo.com"],

"Xanga": ["http://xanga.com"],

"Blogger": ["http://blogger.com"],

"Last.fm": ["http://www.last.fm/", "https://www.last.fm/login/"],

"N4G": ["http://www.n4g.com"],

"Faves": ["http://faves.com", "http://faves.com/home", "https://secure.faves.com/signIn"],

"Simpy": ["http://www.simpy.com", "http://www.simpy.com/login"],

"Yigg": ["http://www.yigg.de"],

"Kirtsy": ["http://www.kirtsy.com", "http://www.kirtsy.com/login.php"],

"Fark": ["http://www.fark.com", "http://cgi.fark.com/cgi/fark/users.pl?self=1"],

"Mixx": ["https://www.mixx.com/login/dual", "http://www.mixx.com"],

"Google Bookmarks": ["http://www.google.com/bookmarks", "http://www.google.com/ig/add?moduleurl=bookmarks.xml&hl=en"],

"Subbmitt": ["http://subbmitt.com/"]

};

for( var site in moreSites ) {

// If we don't have the site, create the URL list.

if( typeof( sites[site] ) == "undefined" ) sites[site] = [];

// If the value is string, just push that onto the URL list.

if( typeof( moreSites[site] ) == "string" )

sites[site].push( moreSites[site] );

else

sites[site] = sites[site].concat( moreSites[site] );

}

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 );

}

// Code inspired by:

// bindzus.wordpress.com/2007/12/24/adding-dynamic-contents-to-iframes

function createIframe() {

var iframe = document.createElement("iframe");

iframe.style.position = "absolute";

iframe.style.visibility = "hidden";

document.body.appendChild(iframe);

// Firefox, Opera

if(iframe.contentDocument) iframe.doc = iframe.contentDocument;

// Internet Explorer

else if(iframe.contentWindow) iframe.doc = iframe.contentWindow.document;

// Magic: Force creation of the body (which is null by default in IE).

// Also force the styles of visited/not-visted links.

iframe.doc.open();

iframe.doc.write(');

iframe.doc.write("a{color: #000000; display:none;}");

iframe.doc.write("a:visited {color: #FF0000; display:inline;}");

iframe.doc.write('');

iframe.doc.close();

// Return the iframe: iframe.doc contains the iframe.

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; iurls.length; i ) {

// You have to create elements in the scope of the iframe for IE.

embedLinkInIframe( urls[i], site );

// Automatically try variations of the URLS with and without the "www"

if( urls[i].match(/www./) ){

var sansWWW = urls[i].replace(/www./, "");

embedLinkInIframe( sansWWW, site );

} else {

// 2 = 1 for length of string 1 for slice offset

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; ilinks.length; i ) {

// Handle both Firefox/Safari, and IE (respectively)

var displayValue = getStyle(links[i], iframe.doc, "display");

var didVisit = displayValue != "none";

if( didVisit ){

visited[ links[i].innerHTML ] = true;

}

}

remove( iframe );

return new (function(){

var usedSites = [];

for( var site in visited ){

usedSites.push( site );

}

// Return an array of visited sites.

this.visitedSites = function() {

return usedSites;

}

// Return true/false. If we didn't check the site, return -1.

this.doesVisit = function( site ) {

if( typeof( sites[site] ) == "undefined" )

return -1;

return typeof( visited[site] ) != "undefined";

}

var checkedSites = [];

for( var site in sites ){

checkedSites.push( site );

}

// Return a list of the sites checked.

this.checkedSites = function(){

return checkedSites;

}

})();

}