Convert OR map the string value to the id of existing form element.

Convert OR map the string value to the id of existing form element.

Hi All,
 
I have a string value fetching from the query string.This string value is the id of one of the form elements.
So, In clientside using JQuery I want to convert this string value to id of form element and then set the CSS style to it.
 
 
Thanks & Regards,
Gopi Krishna T