Get the HTML table <thead> element using query

[algadeed]

I would like to add columns to the heading section of my html table using jquery.This is the definition of the table:\[code\]<table id="grid"> <thead> <tr> </tr> </thead> <tbody> </tbody></table>\[/code\]And despite I tried to get the reference to append a new th element this way:\[code\]$("#grid thead").find("tr").append("<th> elem </th>");\[/code\]I still haven't succeed to do it. What should I write to refer to the first row of the heading? Thanks for your help.