Contador de tempo para palestras

countdown.js

<script>
var timerFont = "sans-serif"
var fontSize = 256
var fontUnit = "pt"

var normalBackColor = "palegreen";
var normalForeColor = "navy";

var warnBackColor = "yellow";
var warnForeColor = "navy";

var alarmBackColor = "red";
var alarmForeColor = "white";

var doneBlink = false;
var blinkSwapped = false;       // True if blink state has colors swapped
                                // ..at the moment

var timeLeft = 300;
var warnTime = 60
var alarmTime = 30

var roundTo = 10;
var warnRoundTo = 5;
var alarmRoundTo = 1;

function update()
    {
    display()
    var now = new Date()
    now = now.getTime()
    var left = target - now
    if (left > 0  ||  doneBlink)
	{
	var nextUpdate = left % 1000
	if (nextUpdate == 0)
	    nextUpdate = 1
        else if (nextUpdate < 0)
            nextUpdate += 1000
	setTimeout("update()", nextUpdate)
	}
    }

function display()
    {
    var now = new Date()
    now = now.getTime()
    var left = target - now
    // Round to nearest second
    if (left % 1000 < 500)
	left = Math.floor(left / 1000);
    else
	left = Math.ceil(left / 1000);
    if (left < 0)
	left = 0
    // Round up to multiple of n
    var round = roundTo
    if (left <= alarmTime)
	round = alarmRoundTo
    else if (left <= warnTime)
	round = warnRoundTo
    var rounded = Math.floor((left + round - 1) / round) * round
    var minutes = Math.floor(rounded / 60)
    var seconds = rounded % 60
    var sec = seconds
    if (seconds < 10)
	sec = "0" + seconds
    document.getElementById("countdown").innerHTML = minutes + ":" + sec
    if (left <= 0  &&  doneBlink)
	{
	// Blink every two seconds.  Blinking is done by swapping the
        // foreground and background colors.
        blinkSwapped = !blinkSwapped
        if (blinkSwapped)
            {
            document.getElementById("countdown").style.color = alarmForeColor
            document.getElementById("countdown").style.backgroundColor = alarmBackColor
            }
        else
            {
            document.getElementById("countdown").style.color = alarmBackColor
            document.getElementById("countdown").style.backgroundColor = alarmForeColor
            }
	}
    else if (left <= alarmTime)
	{
	document.getElementById("countdown").style.color = alarmForeColor
	document.getElementById("countdown").style.backgroundColor = alarmBackColor
	}
    else if (left <= warnTime)
	{
	document.getElementById("countdown").style.color = warnForeColor
	document.getElementById("countdown").style.backgroundColor = warnBackColor
	}
    }

//
// Set up a dictionary that has all our default variables
//
var dictionary = []

dictionary['timerFont'] = timerFont
dictionary['fontSize'] = fontSize
dictionary['fontUnit'] = fontUnit
dictionary['normalBackColor'] = normalBackColor
dictionary['normalForeColor'] = normalForeColor
dictionary['warnBackColor'] = warnBackColor
dictionary['warnForeColor'] = warnForeColor
dictionary['alarmBackColor'] = alarmBackColor
dictionary['alarmForeColor'] = alarmForeColor
if (doneBlink)
    dictionary['doneBlink'] = "true"
else
    dictionary['doneBlink'] = "false"
dictionary['timeLeftMinutes'] = Math.floor(timeLeft / 60)
dictionary['timeLeftSeconds'] = timeLeft % 60
dictionary['warnTime'] = warnTime
dictionary['alarmTime'] = alarmTime
dictionary['roundTo'] = roundTo
dictionary['warnRoundTo'] = warnRoundTo
dictionary['alarmRoundTo'] = alarmRoundTo

//
// Parse name/value pairs from the URL.
//
// First, strip off the leading '?'
var searchString = document.location.search;
searchString = searchString.substring(1);

var nvPairs = searchString.split("&");
// Now loop through the pairs, and extract what we want
for (i = 0; i < nvPairs.length; i++)
    {
    var nvPair = nvPairs[i].split("=");
    var name = nvPair[0];
    var value = nvPair[1];
    dictionary[name] = value
    }

//
// Pick out all variable values that we allow to be controlled from
// the URL
//
timerFont = dictionary['timerFont']
fontSize = dictionary['fontSize']
fontUnit = dictionary['fontUnit']
if (fontUnit == "pct")
    fontUnit = "%"
normalBackColor = dictionary['normalBackColor']
normalForeColor = dictionary['normalForeColor']
warnBackColor = dictionary['warnBackColor']
warnForeColor = dictionary['warnForeColor']
alarmBackColor = dictionary['alarmBackColor']
alarmForeColor = dictionary['alarmForeColor']
if (dictionary['doneBlink'] == "true") 
    doneBlink = true
else
    doneBlink = false
timeLeft = +dictionary['timeLeftMinutes'] * 60 + (+dictionary['timeLeftSeconds'])
warnTime = +dictionary['warnTime']
alarmTime = +dictionary['alarmTime']
roundTo = +dictionary['roundTo']
warnRoundTo = +dictionary['warnRoundTo']
alarmRoundTo = +dictionary['alarmRoundTo']

var now = new Date();
now = now.getTime()
var target = now + timeLeft * 1000

document.write("<center><span id='countdown' "
  + "style='background-color:" + normalBackColor
  + "; color:" + normalForeColor
  + "; font-size:" + fontSize + fontUnit
  + "; font-family: " + timerFont
  + "'></span></center>");

setTimeout("update()", 1000)
display()
</script>