UserData usage summary produced by lanyu_javascript skills

Application Scope
UserData is a storage space specially opened by Microsoft in the system for IE, so it only supports the combination of Windows IE. The actual test was in 2000 (IE5.5), XP (IE6, IE7 ), it can be used normally under Vista (IE7). Where is

?
Under XP, it is usually located in C:Documents and Settings username UserData. Sometimes it is located in C:Documents and SettingsusernameApplication DataMicrosoftInternet ExplorerUserData.

Under Vista, located in C:UsersusernameAppDataRoamingMicrosoftInternet ExplorerUserData.

Capacity
The web page production manual says this:

Security Zone
Document Limit (KB)
Domain Limit (KB)

Local Machine
128
1024

Intranet
512
10240

Trusted Sites
128
1024

Internet
128
1024

Restricted
64
640


When used online, the size limit of a single file is 128KB, under one domain name A total of 1024KB files can be saved, and there should be no limit to the number of files. In restricted sites, these two values ​​​​are 64KB and 640KB respectively, so if various circumstances are taken into account, it is best to control a single file to be less than 64KB.

How to use?
Use the following JS statement to create an object that supports UserData:

o = document.createElement('input');
o.type = "hidden";
o. addBehavior ("#default#userData");
//UserData.o.style.behavior = "url('#default#userData')" ;
//The above statement has the same effect
document.body.appendChild(o);

To put it bluntly, UserData is a Behavior in the style, so it is the same when written like this:




UserData can be bound to most html tags, Specifically:

A, ACRONYM, ADDRESS, AREA, B, BIG, BLOCKQUOTE, BUTTON, CAPTION, CENTER, CITE, CODE, DD, DEL, DFN, DIR, DIV, DL, DT, EM, FONT , FORM, hn, HR, I, IMG, INPUT type=button, INPUT type=checkbox, INPUT type=file, INPUT type=hidden, INPUT type=image, INPUT type=password, INPUT type=radio, INPUT type=reset , INPUT type=submit, INPUT type=text, KBD, LABEL, LI, LISTING, MAP, MARQUEE, MENU, OBJECT, OL, OPTION, P, PLAINTEXT, PRE, Q, S, SAMP, SELECT, SMALL, SPAN, STRIKE , STRONG, SUB, SUP, TABLE, TEXTAREA, TT, U, UL, VAR, XM

UserData object has the following attributes and methods:

Attribute
Description

expires
Set or read the file expiration time

XMLDocument
Read the XML DOM of the file

Method
Description

getAttribute
Read the value of the specified attribute

load
Open the file

removeAttribute
Remove the specified attribute

save
Save the file

setAttribute
Assign a value to the specified attribute


The UserData file is actually an XML file, and the string is saved through the file name->attribute, such as the following code:

o.setAttribute("code", "hello world!");
o.save("baidu");

After execution, a baidu[1].xml file will be generated in the UserData folder , the content is:


A file can have multiple attributes, which means it can store a variety of different data.

In the music box link saving project, a UserData class is encapsulated, so that UserData can be used more conveniently. The code is as follows:

Copy code The code is as follows:

/**@class defines the operation of userdata*/
var UserData = {
// Define userdata object
o : null,
// Set file expiration time
defExps: 365,
//Initialize userdate object
init: function(){
if(!UserData.o){
try{
UserData.o = document.createElement('input') ;
UserData.o.type = "hidden";
//UserData.o.style.behavior = "url('#default#userData')" ;
UserData.o.addBehavior ("# default#userData");
document.body.appendChild(UserData.o);
}catch(e){
return false;
}
};
return true;
},
// Save the file to the userdata folder f-file name, c-file content, e-expiration time
save : function(f, c, e){
if( UserData.init()){
var o = UserData.o;
// Keep the object consistent
o.load(f);
// Store the incoming content as a property
if(c) o.setAttribute("code", c);
//Set file expiration time
var d = new Date(), e = (arguments.length == 3) ? e : UserData.defExps;
d.setDate(d.getDate() e);
o.expires = d.toUTCString();
// Save as the specified file name
o.save (f);
}
},
// Read the specified file from the uerdata folder and return it as a string. f-File name
load: function(f){
if(UserData.init()){
var o = UserData.o;
// Read file
o.load (f);
// Return file content
return o.getAttribute("code");
}
},
// Check whether the userdata file exists f-file name
exist : function(f){
return UserData.load(f) != null;
},
// Delete the specified file f-file name in the userdata folder
remove : function (f){
UserData.save(f, false, -UserData.defExps);
}
//End of UserData function definition
};