Cookie expiry time

[greencode]

I'm struggling a bit here. I found this code and I can't figure out how to be in total control of how long the cookie is stored for on the users machine. I've set it up but it seems to expire around 5 years time and I've no real idea why?!

I have this as as the cookie script:

<script>

function SetCookie(c_name,value,expiredays)
{
var exdate=new Date()
exdate.setDate(exdate.getDate()+expiredays)
document.cookie=c_name+ "=" +escape(value)+
((expiredays==null) ? "" : ";expires="+exdate.toGMTString())
}

</script>

and then when the user clicks this button it stores the cookie.

<a href="#" onClick="SetCookie('mycookie','mycookie','30')">Allow Cookies</a>

I just need to know how to set the expiry date for 365 days time?

Any ideas, help or advice would be much appreciated.

[Fotiman]

toGMTString is deprecated and should not be used. Use toUTCString instead.
Instead of setDate, use setTime:

exdate.setTime(exdate.getTime() + (1000 * 60 * 60 * 24 * expiredays));

setTime takes a value in ms, and getTime returns a value in ms. So get the current time in ms, then multiply your expiredays value by 24 to get the number of hours, multiply that by 60 to get the number of minutes, multiply that by 60 to get the number of seconds, and multiply that by 1000 to get the number of ms. Then, as I mentioned, use toUTCString instead of toGMTString.

Hope that helps.