JavaScript Tutorial/Event/Event Handler

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Add event handler listener to document

<html> 
<head> 
<title>W3C DOM Event Propagation</title> 
<script type="text/javascript"> 
function init() { 
    document.addEventListener("click", docEvent, true); 
} 
function docEvent(evt) { 
    alert("Document level."); 
} 
</script> 
</head> 
<body onload="init()"> 
</body> 
</html>


Add event listener to elements in a form

<html>
<head>
<title></title>
<script type="text/javascript">
function writeX(evnt) {
   document.write("Capturing" + evnt.target + " " + evnt.currentTarget);
   return true;
}
function setup(evnt) {
   document.addEventListener("click",writeX,true);
   document.forms[0].addEventListener("click",writeX,true);
   document.forms[0].elements[0].addEventListener("click",writeX,true);
}
setup();
</script>
<body>
<form>
     <input type="submit" value="Submit" /><br>
</form>
</body>
</html>


Add event listener to form

<html>
<head>
<title></title>
<script type="text/javascript">
function writeX(evnt) {
   document.write("Capturing" + evnt.target + " " + evnt.currentTarget);
   return true;
}
function setup(evnt) {
   document.addEventListener("click",writeX,true);
   document.forms[0].addEventListener("click",writeX,true);
   document.forms[0].elements[0].addEventListener("click",writeX,true);
}
setup();
</script>
<body>
<form>
     <input type="submit" value="Submit" /><br>
</form>
</body>
</html>


Bubble up events (Firefox)

<html>
<head>
<title></title>
<script type="text/javascript">
function writeX(evnt) {
   document.write("Capturing" + evnt.target + " " + evnt.currentTarget);
   return true;
}
function setup(evnt) {
   document.addEventListener("click",writeX,false);
   document.forms[0].addEventListener("click",writeX,false);
   document.forms[0].elements[0].addEventListener("click",writeX,false);
}
setup();
</script>
<body>
<form>
     <input type="submit" value="Submit" /><br>
</form>
</body>
</html>


Capturing events

<html>
<head>
<title></title>
<script type="text/javascript">
function writeX(evnt) {
   document.write("Capturing" + evnt.target + " " + evnt.currentTarget);
   return true;
}
function setup(evnt) {
   document.addEventListener("click",writeX,true);
   document.forms[0].addEventListener("click",writeX,true);
   document.forms[0].elements[0].addEventListener("click",writeX,true);
}
setup();
</script>
<body>
<form>
     <input type="submit" value="Submit" /><br>
</form>
</body>
</html>


Event Bubbling (Firefox)

<html>
<head>
<title>Event Bubbling</title>
<script type="text/javascript">
function mouseDown(nsEvent) {
  var theEvent = nsEvent ? nsEvent : window.event;
  var locString = "X = " + theEvent.screenX + " Y = " + theEvent.screenY;
  var theSrc = theEvent.target ? theEvent.target : theEvent.srcElement;
  document.write(locString + " " + theSrc);
}
document.onmousedown=function (evnt) {
   var theEvnt = evnt? evnt : window.event;
   document.write(theEvnt.type);
}

window.onload=function () {
   document.getElementById("first").onmousedown=mouseDown;
   document.getElementById("second").onmousedown=function () {
      document.write("Second event handler");
   }
}
</script>
</head>
<body>
<div id="first" style="padding: 20px; background-color: #ffff0; width: 150px">
  <div id="second" style="background-color: #ff0000; width: 100px; height: 100px"></div>
</div>
</body>
</html>


Event Handlers and this

<html>
<head>
<title></title>
<script type="text/javascript">
window.onload=setObjects;
function setObjects() {
   document.personData.firstName.onblur=testValue;
}
function testValue() {
   document.write(this.value);
}
</script>
</head>
<body>
<form name="personData">
First Name: <input type="text" name="firstName" />
</form>
</body>
</html>


Inline DOM Event Registration

<html>
<head>
<title>Inline DOM Event Registration</title>
<script type="text/javascript">
function helloMsg() {
    var helloString = "hello there";
    document.write(helloString);
}
function helloTwice() {
    var helloString = "hi again";
    document.write(helloString);
}
window.onload=helloTwice;
</script>
</head>
<body onload="helloMsg();">
</body>
</html>


Preventing Bubble and Capture

<html> 
<head> 
<title>W3C DOM Event Propagation</title> 
<script type="text/javascript"> 
function init() { 
    document.body.onclick = docBodEvent; 
    document.addEventListener("click", docEvent, true); 
    document.forms[0].addEventListener("click", formCaptureEvent, true); 
    document.forms[0].addEventListener("click", formBubbleEvent, false); 
} 
function docBodEvent(evt) { 
    if (evt.target.type == "button") { 
       alert("BODY"); 
    } 
} 
function formCaptureEvent(evt) { 
    if (evt.target.type == "button") { 
        alert("This alert triggered by FORM only on CAPTURE."); 
        if (document.forms[0].stopAllProp.checked) { 
            evt.stopPropagation(); 
        } 
    } 
} 
function formBubbleEvent(evt) { 
    if (evt.target.type == "button") { 
        alert("This alert triggered by FORM only on BUBBLE."); 
        if (document.forms[0].stopDuringBubble.checked) { 
            evt.preventBubble(); 
        } 
    } 
} 
</script> 
</head> 
<body onload="init()"> 
<form> 
<input type="checkbox" name="stopAllProp" />Stop all propagation at FORM
<input type="checkbox" name="stopDuringBubble" />Prevent bubbling past FORM 
<input type="button" value="Button "main1"" name="main1" onclick="alert("button")" /> 
</form> 
</body> 
</html>


Register mouse down event(IE)

<html>
<head>
<title>X/Y Marks the Spot</title>
<script type="text/javascript">
function mouseDown() {
  var locString = "X = " + window.event.screenX + " Y = " + window.event.screenY;
  document.write(locString);
}
document.onmousedown=mouseDown;
</script>
</head>
<body>
</body>
</html>
Источник — «http://wbex.ru/index.php?title=JavaScript_Tutorial/Event/Event_Handler&oldid=8775»