What's the difference of Click-to-focus and focus-by-javascript? - javascript

I met one troublesome web page whose structure is complicated. If one DIV is clicked by mouse, everything is OK. However, if it is focus-ed by javascript(i.e. divElement.focus). The layout turns to messy. This only happens in IE7/8.
So, is there any difference between click-to-focus and focus-by-javascript in IE?

Firing a Javascript focus event does not fire a click event. Without seeing the relevant code, I'm led to guess that some click handler is in place that is not being called in the case where you fire a focus event.
You might try, instead, firing a click:
var clickEvent;
if(document.createEvent) {
clickEvent = document.createEvent('click');
clickEvent.initMouseEvent('click');
divElement.dispatchEvent(clickEvent);
} else {
// Semi-pseudocode for IE, not tested, consult documentation if it fails
clickEvent = document.createEventObject();
divElement.fireEvent('onclick');
}
Or if you're into the jQuery thing:
$(divElement).click();
There's similar solutions for Prototype as well (search for Event.simulate).

The definition of the Focus action is to bring the input (keyboard or mouse) to a certain element, usually an input field. When an element gains focus, an OnFocus event is fired. When it loses focus, an OnBlur event is fired.
What you usually get by clicking is the OnClick event, which is not necessarily related to the above two.

This only happens in IE7/8.
Hmm, then I'm sure it's an IE related bug. Not surprising. If there is legitimate Javascript events involved, then they should fire uniformly across all browsers.

Related

Synchronising browser events in JS

This is a bit of an abstract question, but I've been pondering its usefulness, and maybe it's either already been solved or inspires someone to do something based on it.
Well recently I ran across an issue whereby three browser events were fired, all as the result of a single user interaction: click, blur and focus. When the user clicks from one input to another, these events occur; and a similar set occur when the user tabs from one to another.
The trouble I had was that they fired in this order: blur, focus, click. It meant that, if the blur event caused DOM changes, the click event could be affected. I really wanted click, blur, focus - but that's not what the browser gave me.
I figured a general utility could be produced, capturing and cancelling browser events, then synchronising them and firing a single handler for all three. Perhaps extending the Event class so that the event could be reinstated.
Is there a more abstract design pattern I can use here? Something that will allow me to set up an arbitrary number of event listeners, and then fire a single event when all are complete? Does it have an implementation already? All advice welcome.
Dont need to break head around this! you can always trigger these events Programmatically
Note: object referenced here is any element selected using javascript selector.
Initially onBlur & onFocus do event.preventDefault which allows onClick to do its job first
var clicked=false;
object.onblur = function(e) {
if (!clicked) {
e.preventDefault
}
};
object.onfocus = function(e) {
if (!clicked) {
e.preventDefault
}
};
inside click event undo the above preventions and trigger the events in the order you wanted
object.onclick=function(){
clicked=true;
//Do anything
object.unbind('blur'); //this do undo prevent default
object.unbind('focus'); //this do undo prevent default
object.blur(); //in order you want
object.focus();
//make sure to put condition if click clicked
};
Thats it ! Hope it helps

Cannot get focus to return to div after input blurs

http://jsfiddle.net/NsRyr/1/
I am totally stumped on this. Here's what I'm trying to do : I have a div element (call it #keys) that I'm using to handle keypress events.
HTML:
<div id="#keys" tabindex="1">Focus</div>
JS:
$('#keys').keydown(function () {
$('#log').append('*'); // just note that an event happened
});
This works as expected -- as long as #keys is focused, I can receive keypress events and respond to them. In addition, I can set focus to other div elements and the keypress events will no longer be handled by #keys. I can then re-focus the div (e.g., by clicking on it directly, or by responding to a click event on another DOM element) and keypress events are handled as I expect.
So far, so good. The problem that I've come across is that if I focus an input element and then try to re-focus #keys by setting a blur handler that's activated after tabbing away from the input, the #keys div does not receive focus ! It works fine if I blur away from the input by clicking, but not if I use the keyboard.
$('#input').blur(function () {
$('#log').append('blur'); // note that a blur happened
$('#keys').focus();
});
I think the essence of this question is, why doesn't my blur handler on #input seem to work properly when tabbing away from the input (but it does work properly when clicking away) ? Is this just a browser quirk ? (I am using Chrome 30.0.1599.101 on Mac OS.)
This is my first SO question regarding JS, so please let me know what additional detail I can provide to describe the situation.
(Edit : Interestingly, it seems to work fine if I shift-tab away from #input. Still confused what's happening here ; appears to be some sort of tabindex-related issue ?)
I don't have commenting privileges yet, so I'll have to answer, but please mods should change this, because it's basically a duplicate.
Here's the fix to your fiddle:
http://jsfiddle.net/NsRyr/3/
The issue (as described in this answer) is that the blur event fires before the change is done, so the focus needs to be sent down the stack to happen after. Adding a timer deals with the issue.
The line I changed was:
setTimeout($('#keys').focus.bind($('#keys')), 0);
That makes it so it'll wait until the new focus event is completed before firing off the handler.

Single user action firing two events - second event doesn't trigger

I’m running into this issue where a single action by the user is supposed to trigger two events but it only triggers the first one.
The scenario:
A user enters some text into a special field that modifies the layout on focusout , after entering the text, without leaving the field, they click a button.
What’s happening?
I have a focusout event on a text box and click event on a button. What I see is the focusout event gets fired but the click event never does.
I’ve encapsulated this in a jsfiddle:
http://jsfiddle.net/fCz6X/13/
$('#theText').focusout(function (){
$("#focusevent").text("Focusevent");
console.log("focus");
});
$('#theButton').click(function (){
$("#clickevent").text("Clickevent");
console.log("click");
});
So if you click in the text field then click the button I’d expect both events to fire, but we only see the focus out event.
I put in a temporary fix for this by having the mousedown event fire the button instead of a click event (this fires before the focusout event) but that is causing some other behaviors and issues that I don’t want to see. Due to those I think optimal solution is finding a way to get the focusout and click events to both fire. Does anyone have thoughts on how to fix this problem?
Edit: After seeing initial responses I dug a little deeper, the issue here is that the focusout event is changing the page layout which very slightly pushes the location of the button down. The click event triggers after the focusout is done but since the button is no longer in the exact same location, nothing happens.
Here is an updated fiddle that shows my problem
http://jsfiddle.net/fCz6X/11/
It's because you're calling alert - the focusout event fires, but before the browser recognizes you've clicked the button, the alert box blocks it.
Change your event handler to console.log or something else that's non-obtrusive and you'll be ok.
It is the Alert that is blocking.
Some browser security prevents firing too many window.alert at the time.
When trying with other triggers, it looks. You may try console.log()
$('#theText').on("focusout",function (){
$("#theText").val($("#theText").val()+"flb");
});
$('#theButton').on("click",function (){
$("#theText").val($("#theText").val()+"but");
});
I believe this is because the focusout event fires first, executing the handler, and the alert then prevents the browser from recognizing the click.
Try again with console.log instead of alert - it's less invasive.
As Joe said, the blocking alert call is what is breaking the event. Using a non-blocking call you will see both events.
If you really need to perform an alert like this, though, you can defer calling 'alert' until later using setTimeout()
$('#theText').focusout(function (){
setTimeout(function() { // alert after all events have resolved
alert("focus left text box");
}, 0);
});
Edit: In your updated fiddle the reason the click event never fires is because no click event occurs. If you move the button out from under the mouse on mousedown, there is no followup mouseup which is what initiates the 'click' event.
You may need to reconsider other aspects of your design. Your solution of using 'mousedown' is the best you can achieve because it's the only event that actually occurs.

Blur event stops click event from working?

It appears that the Blur event stops the click event handler from working? I have a combo box where the options only appear when the text field has focus. Choosing an option link should cause an event to occur.
I have a fiddle example here: http://jsfiddle.net/uXq5p/6/
To reproduce:
Select the text box
Links appear
Click a link
The blur even occurs and the links disappear
Nothing else happens.
Expected behavior:
On step 5, after blur occurs, the click even should also then fire. How do I make that happen?
UPDATE:
After playing with this for a while, it seems that someone has gone to great lengths to prevent an already-occurred click event from being handled if a blur event makes the clicked element Un-clickable.
For example:
$('#ShippingGroupListWrapper').css('left','-20px');
works just fine, but
$('#ShippingGroupListWrapper').css('left','-2000px');
prevents the click event.
This appears to be a bug in Firefox, since making an element un-clickable should prevent future clicks, but not cancel ones that have already occurred when it could be clicked.
Other things that prevent the click event from processing:
$('#ShippingGroupListWrapper').css('z-index','-20');
$('#ShippingGroupListWrapper').css('display','none');
$('#ShippingGroupListWrapper').css('visibility','hidden');
$('#ShippingGroupListWrapper').css('opacity','.5');
I've found a few other questions on this site that are having similar problems. There seem to be two solutions floating around:
Use a delay. This is bad because it creates a race condition between the hiding and the click event handler. Its also sloppy.
Use the mousedown event. But this isn't a great solution either since click is the correct event for a link. The behavior of mousedown is counter-intuitive from a UX perspective, particularly since you can't cancel the click by moving the mouse off the element before releasing the button.
I can think of a few more.
3.Use mouseover and mouseout on the link to enable/disable the blur event for the field. This doesn't work with keyboard tabing since the mouse is not involved.
4.The best solution would be something like:
$('#ShippingGroup').blur(function()
{
if($(document.activeElement) == $('.ShippingGroupLinkList'))
return; // The element that now has focus is a link, do nothing
$('#ShippingGroupListWrapper').css('display','none'); // hide it.
}
Unfortunately, $(document.activeElement) seems to always return the body element, not the one that was clicked. But maybe if there was a reliable way to know either 1. which element now has focus or two, which element caused the blur (not which element is blurring) from within the blur handler. Also, is there any other event (besides mousedown) that fires before blur?
click event triggers after the blur so the link gets hidden. Instead of click use mousedown it will work.
$('.ShippingGroupLinkList').live("mousedown", function(e) {
alert('You wont see me if your cursor was in the text box');
});
Other alternative is to have some delay before you hide the links on blur event. Its upto you which approach to go for.
Demo
You could try the mousedown event instead of click.
$('.ShippingGroupLinkList').live("mousedown", function(e) {
alert('You wont see me if your cursor was in the text box');
});
This is clearly not the best solution as a mousedown event is not achieved the same way for the user than a click event. Unfortunately, the blur event will cancel out mouseup events as well.
Performing an action that should happen on a click on a mousedown is bad UX. Instead, what's a click effectively made up of? A mousedown and a mouseup.
Therefore, stop the propagation of the mousedown event in the mousedown handler, and perform the action in the mouseup handler.
An example in ReactJS:
<a onMouseDown={e => e.preventDefault()}
onMouseUp={() => alert("CLICK")}>
Click me!
</a>
4.The best solution would be something like:
$('#ShippingGroup').blur(function()
{
if($(document.activeElement) == $('.ShippingGroupLinkList'))
return; // The element that now has focus is a link, do nothing
$('#ShippingGroupListWrapper').css('display','none'); // hide it.
}
Unfortunately, $(document.activeElement) seems to always return the
body element, not the one that was clicked. But maybe if there was a
reliable way to know either 1. which element now has focus or two,
which element caused the blur (not which element is blurring) from
within the blur handler.
What you may be looking for is e.relatedTarget. So when clicking the link, e.relatedTarget should get populated with the link element, so in your blur handler, you can choose not to hide the container if the element clicked is within the container (or compare it directly with the link):
$('#ShippingGroup').blur(function(e)
{
if(!e.relatedTarget || !e.currentTarget.contains(e.relatedTarget)) {
// Alt: (!e.relatedTarget || $(e.relatedTarget) == $('.ShippingGroupLinkList'))
$('#ShippingGroupListWrapper').css('display','none'); // hide it.
}
}
(relatedTarget may not be supported in older browsers for blur events, but it appears to work in latest Chrome, Firefox, and Safari)
If this.menuTarget.classList.add("hidden") is the blur behavior that hides the clickable menu, then I succeeded by waiting 100ms before invoking it.
setTimeout(() => {
this.menuTarget.classList.add()
}, 100)
This allowed the click event to be processed upon the menuTarget DOM before it was hidden.
I know this is a later reply, but I had this same issue, and a lot of these solutions didn't really work in my scenario. mousedown is not functional with forms, it can cause the enter key functionality to change on the submit button. Instead, you can set a variable _mouseclick true in the mousedown, check it in the blur, and preventDefault() if it's true. Then, in the mouseup set the variable false. I did not see issues with this, unless someone can think of any.
I have faced a similar issue while using jQuery blur, click handlers where I had an input name field and a Save button. Used blur event to populate name into a title placeholder. But when we click save immediately after typing the name, only the blur event gets fired and the save btn click event is disregarded.
The hack I used was to tap into the event object we get from blur event and check for event.relatedTarget.
PFB the code that worked for me:
$("#inputName").blur(function (event) {
title = event.target.value;
//since blur stops an immediate click event from firing - Firing click event here
if (event.relatedTarget ? event.relatedTarget.id == "btnSave" : false) {
saveBtn();
}
});
$("#btnSave").click(SaveBtn)
As already discussed in this thread - this is due to blur event blocking click event when fired simultaneously. So I have a click event registered for Save Btn calling a function which is also called when blur event's related Target is the Save button to compensate for the click event not firing.
Note: Didnt notice this issue while using native onclick and onblur handlers - tested in html.

jQuery find(':focus') not acting as expected

I'm making a widget that slides in and out of view on hover with showTracker and hideTracker functions. I want to prevent it from sliding out of view if it contains a focussed form element though, so I've got this going:
function hideTracker(){
if($('#tracker').find(':focus').length == 0){
$('#tracker').stop().hide();
}
}
Cool. Now it doesn't hide if the mouse happens to move out if there's a field in focus. Unfortunately, that also means that when the field does lose focus (and it's time for the widget to hide again) it just stays there. The unHover event has been and gone.
So I added this:
$('#tracker *').blur(function(){
hideTracker();
});
And that works too - with one little bug that I need help with!
If the focus moves from one element within the tracker to another which is also within #tracker, the tracker hides. I figured that if($('#tracker').find(':focus').length == 0) would return false, given that the next form element has focus, but I guess it doesn't.
Is it the case that .blur() fires before the next element attains focus?
How can I get around this?
How about something like this?
$('body *').focus(function(){
if(!$(this).is('#tracker *') && $('#tracker:visible').length != 0) hideTracker();
});
Yikes. Tricky. Yes, what's happening is:
mousedown: old form element gets the blur event. $(':focus').length == 0.
mouseup: new form element gets the focus event. $newFormElement.is(':focus') == true.
This is an improvement:
$('#tracker').focusout(function() //basically like $('#tracker, #tracker *').blur(), but "this" is always '#tracker'
{
if(!$(this).is('#tracker:hover')) //for some reason plain old :hover doesn't work, at least on the latest OS X Chrome
hideTracker();
});
But it's not perfect. It only really works if you use the mouse. If you use tab to move between fields (or some other possible mechanism) while your mouse is not hovering over #tracker, it won't work.
Here's another attempt. It's a bit...hackier. The gist is that, instead of handling the blur event, you handle the focus event of the second thing that's focused. But! What if you click something that can't be focused? Blank space on your page? Then no focus event is fired.
Okay. So the trick is: put a tabindex="0" in your root <html> tag. This means that there is always something that can be focused. So there's no way to focus on nothing (at least, I don't think so).
Then you can do this:
$('*').live('focus', function(e)
{
if(!$.contains($('#tracker')[0], this)) //if the new thing you focused on is not a descendant of #tracker
hideTracker();
e.stopPropagation();
});
Eh? So yeah, that's a certified hack. But it's a tough problem, and that's the best I can come up with at this hour.
Thank you all for your answers. Utilising the .focus() event rather than .blur() was a clever way to look at it. Unfortunately, it does raise a couple of browser problems, and I couldn't get any of the above working very robustly.
In the end I decided to use setTimeout(hideTracker, 100); to allow the focus() event to take place before the count of focussed elements within tracker was evaluated. Not ideal, but it's working well and the delay is fairly imperceptible.
Thanks again.

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