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/*
JavaScript Bible, Fourth Edition
by Danny Goodman
John Wiley & Sons CopyRight 2001
*/
<HTML>
<HEAD>
<TITLE>Count Down Timer</TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!--
var running = false
var endTime = null
var timerID = null
function startTimer() {
running = true
now = new Date()
now = now.getTime()
// change last multiple for the number of minutes
endTime = now + (1000 * 60 * 1)
showCountDown()
}
function showCountDown() {
var now = new Date()
now = now.getTime()
if (endTime - now <= 0) {
stopTimer()
alert("Time is up. Put down your pencils.")
} else {
var delta = new Date(endTime - now)
var theMin = delta.getMinutes()
var theSec = delta.getSeconds()
var theTime = theMin
theTime += ((theSec < 10) ? ":0" : ":") + theSec
document.forms[0].timerDisplay.value = theTime
if (running) {
timerID = setTimeout("showCountDown()",1000)
}
}
}
function stopTimer() {
clearTimeout(timerID)
running = false
document.forms[0].timerDisplay.value = "0:00"
}
//-->
</SCRIPT>
</HEAD>
<BODY>
<FORM>
<INPUT TYPE="button" NAME="startTime" VALUE="Start 1 min. Timer"
onClick="startTimer()">
<INPUT TYPE="button" NAME="clearTime" VALUE="Clear Timer"
onClick="stopTimer()"><P>
<INPUT TYPE="text" NAME="timerDisplay" VALUE="">
</FORM>
</BODY>
</HTML>
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