Javascript- Cookies:
Cookies are small bits of information such as a user name or last visit to a web
page. Web pages can set cookies on a user's system and later retrieve them. 'Cookies'
are stored in a user's system.
Definition: Cookies
are a general mechanism which server side connections can use to both store
and retrieve information on the client side of the connection. Using Javascript
and cookies, it is possible to store small bits of information into a user's
system.
Eg: To keep track
of when a user visited a web page or to store user name , we can use cookies.
These 'cookies' reside in the client or user's system.
Following 2 javascript
functions can be used to store and retrieve a cookie
SetCookie
- Sets a cookie
GetCookieValue - Retrieves a cookie value
function
SetCookie(CookieName, CookieValue){
ExpiryDate = new Date();
ExpiryDate.setTime(ExpiryDate.getTime() + 2000*24*60*60*1000);
var ExpiryDateString = "; expires=" + ExpiryDate.toGMTString();
document.cookie = CookieName + "=" + escape(CookieValue)
+ ExpiryDateString;
}
function
GetCookieValue(CookieName)
{
var CookieValue = "";
var DocumentCookie = " " + document.cookie + ";";
var CookieSearchStr = " " + CookieName + "=";
var CookieStartPosition = DocumentCookie.indexOf(CookieSearchStr);
var CookieEndPosition;
if
(CookieStartPosition != -1) {
CookieStartPosition += CookieSearchStr.length;
CookieEndPosition = DocumentCookie.indexOf(";", CookieStartPosition);
CookieValue = unescape(DocumentCookie.substring(CookieStartPosition,
CookieEndPosition));
}
return CookieValue;
}
Complete Source Code for seting and retrieving cookies using javascript:
<form
name="testform">
<script>
function SetCookie(CookieName, CookieValue){
ExpiryDate = new Date();
ExpiryDate.setTime(ExpiryDate.getTime() + 2000*24*60*60*1000);
var ExpiryDateString = "; expires=" + ExpiryDate.toGMTString();
document.cookie = CookieName + "=" + escape(CookieValue)
+ ExpiryDateString;
}
function GetCookieValue(CookieName)
{
var CookieValue = "";
var DocumentCookie = " " + document.cookie + ";";
var CookieSearchStr = " " + CookieName + "=";
var CookieStartPosition = DocumentCookie.indexOf(CookieSearchStr);
var CookieEndPosition;
if
(CookieStartPosition != -1) {
CookieStartPosition += CookieSearchStr.length;
CookieEndPosition = DocumentCookie.indexOf(";", CookieStartPosition);
CookieValue = unescape(DocumentCookie.substring(CookieStartPosition,
CookieEndPosition));
}
return CookieValue;
}
function
changelocation()
{
SetCookie('username', document.testform.username.value)
}
</script>
<HR>
The following is an example of using Cookies. <BR>
Enter a username in the textbox first and then click the
button "Set my Name". <BR>
This will set a cookie, 'username', in your system.<BR>
<HR>
Enter your name here : <input type="text" name="username"
value="myname" >
<BR>
<input type="button" value="Set my Name" onClick="SetCookie('username',
document.testform.username.value)">
<BR>
<input type="button" value="Get my Name" onClick="alert(GetCookieValue('username'))">
<HR>
</form>
