This post was mentioned on Twitter by fstraps: http://3.ly/n61 Debouncing Javascript Methods | great – $(window).resize(function(){console.log(’resized’);}.debounce()); #3lyfic…

It appears that IE clobbers* the event object once the original function call goes out of scope. It should not do this since we are holding a reference to the event object! This is obviously a bug in IE.

There is a work-around: just debounce the portion of the handler that needs to be debounced and process the event in a non-debounced function.

Example:

// the debounced part - notice we don't pass the event object
var ttt = function (code) {
    alert(code);
}.debounce(200);
 
// the attached event handler extracts the keycode ad passes it to the debounced function
this.inputbox.attachEvent('onkeypress', function (e) { ttt((e || window.event).keyCode) });

I hope that helps!

– John

* It’s not really clobbered, but I am not sure how else to explain it. The object exists, but it no longer has any members and raises exceptions if accessed: “Member not found.”

test code here:

var ttt = function(e){
	if(!e && parent.window.event) { e = parent.window.event;}
        alert(e.keyCode); // error !!
 
}.debounce(200,false);
this.inputbox.attachEvent("onkeyup", ttt, false);

Your post is a bit off-topic, but I share your sentiment about Microsoft products so I’ll let it through!

There are some good lessons to learn from your experience that can also be applied to Javascript debouncing:

 • Setting the detection period too high could cause missed events.
 • Setting the detection period too low could cause redundant events.
 • Coordinating multiple debounce routines can be tricky. (In your case, the Shift and other keys probably had different debounce circuitry.)
 • The quality of the underlying system is critical to being able to lower the detection period to a level that is neither missing events nor causing redundant events.

That last point is key. If you’re debouncing native browser events, you don’t really have much choice. However, if you’re debouncing your own methods/events, then fast-performing Javascript can make a huge difference.

Thanks for the post!

Most keyboards have a bounce time of ~8ms. I found out at my expanse when I bought a 50$ Microsoft keyboard which have a bounce time of 15ms, most people will never notice, but I did.

Don’t buy this s**t: http://www.microsoft.com/hardware/mouseandkeyboard/ProductDetails.aspx?pid=083&active_tab=systemRequirements

With this keyboard when I type “Shift + :w + Enter” in Vim to save a document, the computer actually gets “:W + Enter”, which triggers an error in Vim. It’s pretty annoying, I guess Microsoft’s keyboard designer a slow typists.

At first I thought my fingers were becoming lazy, but I realized it was the s***ty Microsoft keyboard when I bought a Razer Lycosa, one of the best keyboard I ever had for programming.

With its 1ms response time this problem *never* occurred once. It also looks pretty bad ass: http://www.razerzone.com/gaming-keyboards/razer-lycosa/razer-lycosa-keyboard