JavaScript DHTML/Development/Timer

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Accessing Document Contents

<HTML>
<HEAD>
<TITLE>Accessing Document Contents</TITLE>
<SCRIPT LANGUAGE="JavaScript"><!--
function createSummary() {
 win2 = open("","window2")
 win2.document.open("text/plain")
 win2.document.writeln("Title: "+document.title)
 win2.document.writeln("Links: "+document.links.length)
 win2.document.writeln("Anchors: "+document.anchors.length)
 win2.document.writeln("Forms: "+document.forms.length)
 win2.document.writeln("Images: "+document.images.length)
 win2.document.writeln("Applets: "+document.applets.length)
 win2.document.writeln("Embeds: "+document.embeds.length)
 win2.document.close()
}
// --></SCRIPT>
</HEAD>
<BODY>
<A NAME="#top"></A>
<form>
<INPUT TYPE="BUTTON" NAME="Help" VALUE="Help"  ONCLICK="alert("Click one of the above images.")">
</FORM>
<SCRIPT LANGUAGE="JavaScript"><!--
setTimeout("createSummary()",5000);
// --></SCRIPT>
</BODY>
</HTML>



A Countdown Timer

/*
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>



A Timeout Processing Example

<HTML>
<HEAD>
<TITLE>Timeout Program</TITLE>
<SCRIPT LANGUAGE="JavaScript"><!--
function setTimer() {
 timer=setTimeout("alert("Too slow!")",10000)
}
function clearTimer() {
 clearTimeout(timer)
 alert("Hi!")
}
// --></SCRIPT>
</HEAD>
<BODY>
<SCRIPT LANGUAGE="JavaScript"><!--
setTimer()
// --></SCRIPT>
<FORM>
<INPUT TYPE="BUTTON" VALUE="Click here within ten seconds." ONCLICK="clearTimer()">
</FORM>
</BODY>
</HTML>



setInterval() and clearInterval() methods

<html>
<head>
<script type="text/javascript">
    var intval=""
    function start_Int(){
        if(intval==""){
          intval=window.setInterval("start_clock()",1000)
      }else{
          stop_Int()
      }
    }
    function stop_Int(){
        if(intval!=""){
          window.clearInterval(intval)
          intval=""
          myTimer.innerHTML="Interval Stopped"
      }
    }
    function start_clock(){
        var d=new Date()
        var sw="am"
        var h=d.getHours()
        var m=d.getMinutes() + ""
        var s=d.getSeconds() + ""
        if(h>12){
          h-=12
          sw="pm"
      }
        if(m.length==1){
          m="0" + m
      }
        if(s.length==1)  {
          s="0" + s
      }
        myTimer.innerHTML=h + ":" + m + ":" + s + " " + sw
    }
</script>
</head>
<body>
<span id="myTimer">Interval Stopped</span>
    <br><br><br>
    <input type="button" value="Start" onclick="start_Int()">
    <input type="button" value="Stop" onclick="stop_Int()">
</body>
</html>



Timer Events Demo

/*
JavaScript Unleashed, Third Edition
by Richard Wagner and R. Allen Wyke 
ISBN: 067231763X
Publisher Sams CopyRight 2000
*/

<head>
<script language="JavaScript">
<!--
     function dailyTask() {
       var tdy = new Date();
       if ((tdy.getHours() == 8) && (tdy.getMinutes() == 30)) {
           alert("Good morning sunshine!")
           clearInterval(timerID)
        }
     }
   
//-->
   
timerID = setInterval("dailyTask()", 10000)
   
</script>
</head>



Timer Events Demo 2

/*
JavaScript Unleashed, Third Edition
by Richard Wagner and R. Allen Wyke 
ISBN: 067231763X
Publisher Sams CopyRight 2000
*/
<head>
<script language="JavaScript">
<!--
     function performProcess() {
        alert("Good morning sunshine!");
     }
   
     function dailyTask() {
        var tdy = new Date();
        if ((tdy.getHours() == 8) && (tdy.getMinutes() == 30)) {
           performProcess()}
           timerID = setTimeout("dailyTask()",10000)
        }
//-->
</script></head>
   
<body onLoad="dailyTask()">
</body>



Using a Timer

/*
Learn How to Program Using Any Web Browser
by Harold Davis 
Apress CopyRight 2004
ISBN: 1590591135
*/
<HTML>
<HEAD>
<TITLE>As time goes by...</TITLE>
<SCRIPT> 
var timerID; 
var x; 
function Thing (name) { 
   this.name = name; 
} 
function fireIt () { 
   var now = new Date(); 
   var displayStr = window.document.theForm.txtFired.value; 
   displayStr += "Hello: " + x.name + " "  + now + "\r\n"; 
   window.document.theForm.txtFired.value = displayStr; 
} 
function startIt (name) { 
   x = new Thing (name); 
   timerID = setInterval("fireIt()", 1000); 
} 
function stopIt() { 
   clearInterval(timerID); 
} 
</SCRIPT>
</HEAD>
<BODY>
<TABLE>
<FORM name="theForm">
<TR>
<TD>Name your object:</TD>
<TD>
<input type=text 
name="txtName">
</TD>
</TR>
<TR>
<TD>
</TD>
<TD>
<input type=button value="Start!" 
   onClick="startIt (txtName.value);">
</TD>
<TD>
<input type=button value="Stop!" 
   onClick="stopIt();">
</TD>
</TR>
<TR>
<TD>
</TD>
<TD>
</TD>
</TR>
<TR>
<TD colspan=2>
<textarea name="txtFired" cols = 60 
rows=20>
</textarea>
</TD>
</TR>
</FORM>
</TABLE>
</BODY>
</HTML>