The Cookie Technology

retrieve cookies with JavaScript

<HTML>
<HEAD><TITLE>JavaScript cookie example II<TITLE><HEAD>
<SCRIPT LANGUAGE = "JavaScript">
    var cookies = document.cookie;
    var cookie = "There was no cookie named username!";
    var searchfor = "username=";
    var start = 0;
    var end = 0;
    if ( cookies.length > 0 )
    {
        start = cookies.indexof ( searchfor );
        if ( start != -1 )
        {
            start += searchfor.length;
            end = cookies.indexof ( ";", start);
            if ( end = = -1 )
            {
                end = cookies.length;
            }
            cookie = " Found a cookie named username with a value of " + cookies.substring( start, end );
        }
    }
    alert ( cookie );
</SCRIPT>
<BODY><P>JavaScript example</P></BODY>
</HTML>

Notes

In JavaScript, cookies are stored as a single string, with each cookie separated by a semicolon. The string with the cookies and their values is stored in the built-in document.cookie object. To find the correct cookie, you have to search through the string. This can be an awkward process.
It's not quite as easy to retrieve a cookie with JavaScript as it is to set one. Several function libraries are available for managing cookies in JavaScript. If you are serious about using cookies with JavaScript, you will be better off if you acquire such a library before you begin programming.