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Prevent blur event on keyboard close

This is for mobile web apps, not native.
I have an autocomplete drop-down that closes on the blur event. But I want to prevent this from happening when the user closes the keyboard on mobile (ie the autocomplete dropdown should stay visible). Is there a way to distinguish a blur event caused by the keyboard closing, and other kinds of blur events? Can I prevent a blur event specifically caused by closing the keyboard in mobile?

Ok, first I would recommend checking your libraries' documentation because they might provide something in their API, although there's nothing I'm aware of. That's the disadvantage of Web Apps: you can't access native functionality.
If you still really want to do it, here's a possible solution. It's ugly, but it might work.
Container on tap function (event)
If !autocomplete return // if you cant see the popup do nothing and blur normally
If (event.target != inputID) AND (event.target != autocID)
CloseAutocomplete()`
Essentially, instead of closing the autocomplete on blur, close it whenever the user taps on your parent container, but not on the input itself or the autocomplete. Depending on how it works, you could extend it to check any tap on screen.

I see you tagged iOS... you can observe keyboard events with UIKeyboardWillHideNotification. [https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIWindow_Class/index.html#//apple_ref/c/data/UIKeyboardWillHideNotification] You may have to do and asynchronous delay to catch that event on with onblur, though.
If you really want to prevent all "other kinds of blur events" you could make your drop-down close on specific events (instead of on blur). For example: when a another field is clicked, navigation, and/or add an 'x' close button next to that drop-down control.

In the blur event listener, test for event.relatedTarget === null. If focus has moved to a different element, event.relatedTarget will refer to that element, but if there is no focus (as is the case when the cause of the blur is keyboard close), event.relatedTarget will be null.

JavaScript: Swipe for Action Pattern Implementation

I have implemented the Swipe for Action Android pattern in my mobile web application (PhoneGap) using JavaScript & CSS animations/transitions.
However, there's one thing that's still eluding me.
I wish, that once the action menu is displayed fully and the user clicks anywhere outside of the action menu (labelled 3 in the figure), the menu should retract and the original item displayed (labelled 1 in the figure).
In a desktop application, one could "capture focus" and perform the transition back to (1) in lostfocus.
What is the JS equivalent of lostfocus event. I see an onfocus and onblur event, but from what I read it's really meant for things that need focus; like input, textarea, etc.
How else could I catch that event I'm interested in, other than putting some code in the touchend of every other element in the page and forcing the retraction of open actions explicitly?

I think you gave the answer yourself. focus and blur are the events to be used for this and they are not exclusively meant for input elements, as you can see here [1].
I'm even trigger the focus event manually in a layer use case: A layer opens and I want to capture the keypress of ESC to close the layer. For this I need to set the focus on the layer as my event handler would not fire otherwise.
To capture the click outside you just need to register for pointerUp or click events on an element that spans the whole screen (it must really cover the whole screen like the body element). Because of the event bubbling the handler will fire as long as nothing else captured and cancelled it.
[1] https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#event-type-blur

javascript drag and drop with partial preventDefault

Gmail handles its drag-and-drop file attachment uploading in a few clever ways:
1) Dragging a file into the browser causes the dropzone to appear. The cursor displays feedback indicating whether you are in the dropzone or not (in windows, a red crossthrough circle is used if outside the dropzone). If you drop inside the window but outside of the dropzone, the drop is intercepted such that the browser's default behavior is prevented (usually navigating away to display the dragged file).
The most obvious way to attempt this is to set dragover handler on the BODY to make the dropzone appear and preventDefault, but what about the cursor change? Is there some way to use dataTransfer.effectAllowed='none'?
2) Dragging text from one part of the window into another part does not trigger the drag-and-drop handling (ie- the dropzone does not appear)--and the preventDefault mentioned in #1 does not kick in.
If I capture the dragover event on the BODY (from #1), then intra-window text dragging is prevented. How do they accomplish both of these at the same time? It seems like this is more complex than it at first might appear.
UPDATE:
I learned two related things while trying to completely address this:
1) It appears that IE will not even trigger the drop event handler if dropEffect='none'... so I decided to only set it to none if e.dataTransfer.types exists (which it does in Chrome & FF, but not in IE). The downside is that the cursor doesn't have the red crossthrough, but at least I can intercept the drop to prevent a navaway. Your best guess for determining whether it was a file drop in IE is if e.dataTransfer.getData('Text')==null. (In my case, I wanted to be able to receive drops of either files or text, so this is how I can tell the difference in IE.)
2) It was non-obvious how Gmail hides the dropzone when you leave the browser. If you use a pure dragleave event on the page, then dragging into any child will trigger the dragleave handler even though you didn't really leave the page. I then noticed that there's a delay in Gmail before the dropzone disappears, so I would guess they use a timer to hide the dropzone (which gets reset on something like dragover). But I've come up with an alternate solution that appears to work so far:
function areXYInside(e){
var w=e.target.offsetWidth;
var h=e.target.offsetHeight;
var x=e.offsetX;
var y=e.offsetY;
return !(x<0 || x>=w || y<0 || y>=h);
}
And then:
$("#page").bind('dragleave', function(e){
if(this!=e.target) return false;
if(!areXYInside(e)){
hideBox();
}
return false;
});

I believe they are setting dataTransfer.effectAllowedon dragover, depending on the dataTransfer.types attribute.
EDIT: I was wrong the first time, here are the actual values for types(in Chrome at least):
- dragging text ["text/html","text","text/plain"]
- dragging a file ["Files"]
Here is a short jsFiddle example to play around with.
You can check more info about drag and drop at w3c or mdc.
EDIT: I managed to implement the exact behavior on Chrome and FF (see here)

Is there a way to "reset" mobile Webkit's pseudo-hover behaviour after the initial hover-triggering click?

I'm working on a website where I'm using Javascript (via JQuery) to add pop-up boxes containing extra information for items in a list. I'm using JQuery's mouseeneter and mouseleave events to make the popups appear and disappear which of course all works fine in desktop browsers.
In Mobile Safari the popup appears when I click an item (which is what I expect and what I want to happen) and I have added an ontouchstart which triggers the mouseleave JQuery event thus hiding any visible pop-up when the user does anything else. This works fine too except that when a user taps an item the pop-up of which they've just looked at and cancelled (either by scrolling or by doing anything else that triggers the ontouchstart event), rather than it showing the pop-up again it activates the link attached to that item.
If a user were to tap another item instead of tapping the same item again then that new item's pop-up would show and then if they were to tap the first item again then that item's pop-up would show. Again, this is both expected and what I want to happen.
It would seem that once an item with a hover event has been tapped and Mobile Safari as been forced to make that event happen, that item is then flagged as having had its hover event triggered and so the next tap doesn't have to pretend to be a hover, it can be a normal click. Tapping another item with a hover event seems to "reset" the flag set for the previous item.
I'd like to be able to 'reset' this flag for myself so that, rather than how things work currently where clicking an item shows the pop-up and the next click on that item, even if the pop-up has been closed, will activate the link, instead when I close the pop-up with my ontouchstart, and so to my mind the item is no longer being "hovered over", a second click on that same item should show the pop-up again and then only by clicking on the item whilst the pop-up is visible should the link activate.
The secret would seem to be in getting Mobile Safari to exit its "pseudo-hover" mode when I use ontouchstart to trigger mouseleave but I have been unable to find anything useful anywhere on exactly what's going on when Mobile Safari pretends to hover over anything and whether any of this is accessible via Javascript events.
I know I could write a version of my pop-up code to work specifically for Mobile Safari but it seems much more efficient to me to get the browser to do most of the hard work of mimicking hover events. If only I could get this final little niggle sorted out.

I'm guessing the hover state is tied into which element has focus rather than as a flag. One tap gives focus, second tap activates the link.
Try closing the pop-up by giving another element focus, and see if that works out any better.
$('body').focus();

tl;dr but try this:
# :hover fix
# e.g.: body:not(.stoppedhovering) .styled:hover
hoverFix = ->
window.clearTimeout hoverFix.delay if hoverFix.delay?
$('body').removeClass 'stoppedhovering'
delayed = -> $('body').addClass 'stoppedhovering'
hoverFix.delay = _.delay delayed, 600
$('*').live 'touchstart', hoverFix

How to give a page focus again so that the space bar pages down in FF?

I have an ajax script with a "get more posts" button that inserts a couple screens/viewports worth of information. In doing this, the document looses focus at some point and thus the default behavior of the space bar (page down) doesn't work in firefox.
How can I focus the document again to regain the default behavior? What components control this behavior?
It works in Chrome and IE (surprisingly), but not FF.
I tried in a callback function: document.body.focus() and document.getElementById('someClickableElement').click(), but no luck.
If I actually click on the page after the content is displayed, then I can scroll again with the space bar.
Since this is a frequently used feature, it's annoying to click "load more", click again, then space to page down.
Thoughts? Suggestions?
EDIT:
Ok, so i was using a YUI button (just a nice looking html "button" element with some css styling) for the interface. i replaced it with a link, and i no longer have this problem.
Interesting that it works as expected in Chrome & IE, and I'm not even using YUI listeners for the event (just the nice-looking buttons). It's handled by jquery's live method (b/c of the event delegation).
Also interesting that I'm not able to programmatically do what I can do physically (ie. "click").
Even if there is some YUI bug, it seems like firefox should be able to regain focus via some javascript action.
VERY WEIRD. Still any input appreciated (more javascript suggestions to try?). I'm somewhat committed to my current interface.

It looks like you need to blur YUI button element. Or do something with tab order between whole document and the YUI button.
So - not to focus() document, but to blur() YUI button.
Alternatively, you may try to apply 'keypress' event simulating 'TAB' key.

I haven't tried this but how about doing a blur() on the body or the window.
window.blur();