javascript

}
burst(e);
thwart(e);
function move(e) {
if (!e) e = window.event;
wrapper.style.left = left + e.clientX - clientX + "px";
wrapper.style.top = top + e.clientY - clientY + "px";
}
function drop(e) {
if (!e) e = window.event;
}
CHAPTER 9 ■ LISTENING FOR EVENTS
Now to prevent the mousemove event object from traversing the DOM tree any further, pass e to
burst(). Note that this is just for Internet Explorer 9, Firefox, Safari, Chrome, and Opera since in Internet
Explorer 8 or earlier the mousemove event has already ended its journey by bubbling up to document.
Note too that there would be no point in passing e to thwart() inasmuch as there is no default action for
a mousemove event.
And with that, we’re done coding move(). So if any one next to you has their ears covered and eyes
closed, give them a poke. Then have them cut and paste our code for move(), which appears here:
function drag(e) {
if (!e) e = window.event;
if (!e.target) e.target = e.srcElement;
var wrapper = e.target.parentNode;
var left = parseInt(queryCascade(wrapper, "left"));
var top = parseInt(queryCascade(wrapper, "top"));
var clientX = e.clientX;
var clientY = e.clientY;
wrapper.style.zIndex = doZ();
addListener(document, "mousemove", move, true);
addListener(document, "mouseup", drop, true);
burst(e);
thwart(e);
function move(e) {
if (!e) e = window.event;
wrapper.style.left = left + e.clientX - clientX + "px";
wrapper.style.top = top + e.clientY - clientY + "px";
burst(e);
}
function drop(e) {
if (!e) e = window.event;
}
}
Writing the Mouseup Event Listener
Now for the mouseup event listener, drop(). First, we want to tell JavaScript not to listen for mousemove
or mouseup events on document. This is where our helper function removeListener() earns its keep.
Remember that to remove an event listener with removeEventListener() or detachEvent(), you must
pass the same parameters that you added the event listener with. With this in mind, let’s cut and paste
our addListener calls within drag(). Then just change addListener to removeListener:
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