Your question (like the other one) shows a misunderstanding of what's going on. Your CGI program isn't "calling" any javascript. It can't -- the CGI runs on the server, and javascript runs in the browser after the page is loaded. Your CGI is outputting an HTML page, which happens to include a button on which is attached a click handler which calls a javascript function. By the time someone clicks the button, the CGI program has already done its job and exited.

For your browser to find that function when a user clicks the button, the function will have to be defined in the HTML file itself (as you discovered) or in a separate javascript file that the HTML file includes with a <script type='text/javascript' src='myfile.js'> sort of tag.