JavaScript Countdown Timer

<style type="text/css">
#txt {
  border:none;
  font-family:verdana;
  font-size:16pt;
  font-weight:bold;
  border-right-color:#FFFFFF
}

</style>
	<!--
    	This script downloaded from www.JavaScriptBank.com
    	Come to view and download over 2000+ free javascript at www.JavaScriptBank.com
	-->

<script language="javascript">
// Created by: Neill Broderick :: http://www.bespoke-software-solutions.co.uk/downloads/downjs.php

var mins
var secs;

function cd() {
 	mins = 1 * m("10"); // change minutes here
 	secs = 0 + s(":01"); // change seconds here (always add an additional second to your total)
 	redo();
}

function m(obj) {
 	for(var i = 0; i < obj.length; i++) {
  		if(obj.substring(i, i + 1) == ":")
  		break;
 	}
 	return(obj.substring(0, i));
}

function s(obj) {
 	for(var i = 0; i < obj.length; i++) {
  		if(obj.substring(i, i + 1) == ":")
  		break;
 	}
 	return(obj.substring(i + 1, obj.length));
}

function dis(mins,secs) {
 	var disp;
 	if(mins <= 9) {
  		disp = " 0";
 	} else {
  		disp = " ";
 	}
 	disp += mins + ":";
 	if(secs <= 9) {
  		disp += "0" + secs;
 	} else {
  		disp += secs;
 	}
 	return(disp);
}

function redo() {
 	secs--;
 	if(secs == -1) {
  		secs = 59;
  		mins--;
 	}
 	document.cd.disp.value = dis(mins,secs); // setup additional displays here.
 	if((mins == 0) && (secs == 0)) {
  		window.alert("Time is up. Press OK to continue."); // change timeout message as required
  		// window.location = "yourpage.htm" // redirects to specified page once timer ends and ok button is pressed
 	} else {
 		cd = setTimeout("redo()",1000);
 	}
}

function init() {
  cd();
}
window.onload = init;
</script>
	<!--
    	This script downloaded from www.JavaScriptBank.com
    	Come to view and download over 2000+ free javascript at www.JavaScriptBank.com
	-->

<form name="cd">
<input id="txt" readonly="true" type="text" value="10:00" border="0" name="disp">
</form>
	<!--
    	This script downloaded from www.JavaScriptBank.com
    	Come to view and download over 2000+ free javascript at www.JavaScriptBank.com
	-->