How to detect if cookie is set in Javascript ?

Question

I have set a session in PHP, which is creating a cookie: PHPSESSID... I can detect this in Chrome & Opera by using document.cookie. However in Forefox, document.cookie also returns cookies set on the page by other domains, e.g. Google Analytics.

In PHP I am setting the sessions like:

session_start();
$_SESSION['source'] = &$ref['source'];
$_SESSION['term'] = &$ref['term'];
session_write_close();

I need to be able to detect if this session is set in Javascript, by locating the cookie. What is the best way to go about this?

At the moment I am just using:

document.cookie.indexOf( 'PHPSESSID' )

which seems like a bit of a botch.

TheSavage · Accepted Answer · 2014-01-18 20:14:14Z

1

The document.cookie property will return all the cookies. While your indexOf will work, it will break if your cookies actual data contains 'PHPSESSID'. It will also match the following cookie 'MYPHPSESSIDIDIT', as it contains your cookie name.

You could parse the cookies with the following function (not tested):

function getCookieValue(name)
{
    // find cookie entry in middle?
    var s=document.cookie,
        c=s.indexOf("; "+name+"=");

    if(c==-1)
    {
        // no, is it at the start?
        c=s.indexOf(name+"=");
        if(c!=0) return null;
    }

    // get length of value
    var l=c+name.length+1,
        e=s.indexOf(";",l);

    // is it at the end?
    if(e==-1) e-s.length;

    // cut out the value
    return s.substring(l,e);
}

Hope this helps

answered Jan 18, 2014 at 20:14

TheSavage

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phpCore · Accepted Answer · 2014-01-18 20:09:05Z

1

Use this Jquery plugin, it's so cool.

https://github.com/carhartl/jquery-cookie

You can use it like this way:

if($.cookie('PHPSESSID') != undefined){
 //PHPSESSID exists
}

answered Jan 18, 2014 at 20:09

phpCore

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