How do I use a Javascript variable in PHP?

Hi all, I hope this is the right place to pose my question, so here goes: - I have a javascript function called calcMonth() and given a number it will return a date i.e. month = calcMonth( 57 ) - month will be 'sept 2002' The problem Im having is at the beginning of my PHP file Im calling this calcMonth() then doing a load of php stuff and then trying to use the javascript month variable, but to no avail: - print "<td><input type=text class=claimreadonly readonly name=POST_monthdisp value=javascript:month; size=10 tabindex=99></td>"; The result is, the browser displays the words 'javascript:month;' - not a month number I`ve looked everywhere for an answer from persistent javascript data to using framesets to hold the variable but to no avail. I know its quite a bit of javascript, but its mixed in with PHP too so I thought it`d be the right place. Anyways, I hope someone can provide the answer to my problem. Thanks in advance, Tom