Snippet call

Hi,
I have a javascript code and I want to call a snippet that stores a value in a placeholder. The problem is that I want to pass the value stored in a var and I am passing the name. The code is as follows:

var rid = getselectedid();
[[save_id?&cod=rid]];

In save_id there’s just a call to setplaceholder()

$modx->setPlaceholder(reg_id,$cod);

does anybody know how to pass the rid value??
Thanks

Javascript is not executed until the server processes the PHP on the server. You cannot set server-side processed variables with javascript variables that will not exist until the page is rendered.

Is there anyway I can save a var’s value generated in javascript code?

AJAX and the HTTP request methods.
http://www.w3schools.com/ajax/default.asp