Collection of JavaScript code snippets

Detect if JavaScript is enabled

That one is tricky and I had no idea how to detect and react to this in the same request. However, for my purpose, I do not need to take action in the same request: I only want to tell a CGI-bin whether it should serve a page optimised for JavaScript enabled browsers. This is solved by simply adding a '&js=1' parameters to the link with JavaScript. Obviously, if JavaScript is disabled, the parameter will be missing.
function detect_javascript(cl) { var nodes, i, s; nodes = document.getElementsByTagName('a'); for (i = 0; i < nodes.length; i++) { if(nodes[i].className === cl) { s = nodes[i].href; nodes[i].href=s+'&js=1'; } } }
To tell the JavaScript which links shall be changed, you have to tag the links with a specific class
<a class="changeme" href="/cgi-bin/test.cgi">Test</a>
and pass this class to the JavaScript function call:
<script type="text/javascript"> detect_javascript('changeme'); </script>

Detect screen size

function detect_window_size() { var myWidth = 0, myHeight = 0; if(typeof(window.innerWidth) == 'number') { // All sane browsers myWidth = window.innerWidth; myHeight = window.innerHeight; } else if(document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight)) { // IE 6+ in 'standards compliant mode' myWidth = document.documentElement.clientWidth; myHeight = document.documentElement.clientHeight; } else if(document.body && (document.body.clientWidth || document.body.clientHeight)) { // IE 4 compatible myWidth = document.body.clientWidth; myHeight = document.body.clientHeight; } // window.alert('Width = ' + myWidth ); // window.alert('Height = ' + myHeight ); }