I'm trying to implement a drag'n'drop upload input for a web app. Detecting drag start and end and appropriate drop target styling works flawlessly, though as soon as I drop an image file on the target, it opens in the browser. I know this has been asked pretty often on Stack Overflow, but I couldn't find a solution anywhere yet.
What I do see is: Listeners for dragenter, dragstart and dragend fire correctly, while drop does not. Please see the code below:
(Note: The app object is just a simple, custom abstraction object, nothing special about it. The app.on method calls addEventListener and attaches the event wrapped in a try-catch block.)
Attaching the events
app.on('drag dragover dragstart', app.elements.pictureDropArea, app.events.startedDragging, true);
app.on('dragenter', app.elements.pictureDropArea, app.events.isDragging);
app.on('dragleave dragend', app.elements.pictureDropArea, app.events.stoppedDragging);
app.on('drop', app.elements.pictureDropArea, app.events.isDropped);
The individual events
app.events.startedDragging = function(event) {
event.preventDefault();
event.stopPropagation();
return false;
};
app.events.isDragging = function(event) {
event.preventDefault();
event.stopPropagation();
app.elements.pictureDropArea.classList.add('dragged-over');
return false;
};
app.events.stoppedDragging = function(event) {
event.preventDefault();
event.stopPropagation();
app.elements.pictureDropArea.classList.remove('dragged-over');
return false;
};
app.events.isDropped = function(event) {
event.preventDefault();
event.stopPropagation();
console.log('drop event fired.');
var file = event.dataTransfer.files[ 0 ];
console.log(file);
return false;
};
Found it accidentally when I applied the same events to the body. It seems like there needs to a listener for dragover on the document body with the usual preventDefault and stopPropagation stuff:
app.on('dragover', document.body, function(event) {
event.preventDefault();
event.stopPropagation();
return false;
});
God, I hate this API so much...
Related
I have a technical issue and I am not sure what the best way is to solve it.
Basically im working on an audio progress bar where the user can change the position of the song. This should be done by either clicking or by keeping the mousedown and moving it.
elem.addEventListener("mouseup", function(event){
elem.removeEventListener("mousemove", fn);
});
elem.addEventListener("mousedown", function(event){
elem.addEventListener("mousemove", function(event){
// Stuff to do
}, fn);
});
So essentially:
If mouse is held down and then moved do something. If mouse is released prevent the trigger of mousemove.
I know if I continue with this it might work but it looks like a horrible mess to me. I dont want to pick up bad habits.
My question is: How do I make make this work using best practices?
Note: I also tried the following:
function fn(event) {
if(event.button == 0) {
elem.addEventListener("mousemove", function(event){
// Stuff to do
});
}
}
What i'm missing here !
Don't add/remove the listener, just set a variable at trigger actions accordingly:
var isMousedown = false;
elem.addEventListener("mousedown", function (event) {
isMousedown = true;
}
elem.addEventListener("mouseup", function (event) {
isMousedown = false;
});
elem.addEventListener("mousemove", function (event) {
if (isMousedown) {
// do stuff
} else {
// do different stuff, or nothing
}
});
You may even want to put the mousedown/mouseup listeners on the parent (or even the root element) to avoid scenarios where the mouseup happens outside of the target, if that is a possibility in your case.
I am working on a firebug like javascript element selector, but cannot figure out how to stop all JavaScript events from firing when clicked. The firebug lite plugin (https://getfirebug.com/firebuglite) is doing exactly what I want, but cannot figure out what they are doing.
Any help would be appreciated.
Senario:
User selects element inspector
User clicks on element
onClick, mousedown, mouseup should NOT fire
I have tried the following with no luck:
function stopEvents(el){
for(var key in window) {
if (key.indexOf("on") == 0)
el.addEventListener(key.substr(2), stop, false);
}
}
function StopEvent(pE)
{
stopEvents(pE);
if (!pE)
if (window.event)
pE = window.event;
else
return;
if (pE.cancelBubble != null)
pE.cancelBubble = true;
if (pE.stopPropagation)
pE.stopPropagation();
if (pE.preventDefault)
pE.preventDefault();
if (window.event)
pE.returnValue = false;
if (pE.cancel != null)
pE.cancel = true;
}
EDIT:
$('.somediv').on("click", function(e){
//Stop bubbling and propagation
StopEvent(e);
//EDIT: Still not working with this
e.stopImmediatePropagation();
//RUN only my code here
console.log("My code is running still");
return false;
});
If there is another library such as YUI binding events to the same DOM element. It will fire there event after mine. I cannot seem to hijack the event to stop this from happening.
EDIT:
I cannot use disabled because I need to be able to fire my event. If I did the following, I wouldn't be able to fire the above event. I cannot attach a parent event either because the DOM will stop firing all events on the Tree for that node.
$('.somediv').on("mouseover", function(e){
$(this).attr("disabled", "disabled");
});
EDIT:
The events I want to disable are already created before my script runs. These events could be any javascript library such as YUI, Dojo, jQuery, JavaScript etc...
Disabling all events on the page is very easy. Hard part is to restore them when needed.
document.body.innerHTML = document.body.innerHTML;
This will effectively remove all events bound to DOM nodes by replacing the DOM with it's "virgin" copy.
Most of the time user won't even notice the redraw.
You can't "disable" all of them without also intercepting the actual event binding, so you'd have to end up with something like this:
(function(prototypes) {
prototypes.forEach(function(prototype) {
var eventTracker = {};
var oldAEL = prototype.addEventListener;
prototype.addEventListener = function(a,b,c) {
if (!eventTracker[a]) { eventTracker[a] = true; }
return oldAEL.call(this, a, function(evt) {
console.log(a, eventTracker[a]);
if(eventTracker[a] === true) {
b(evt);
}
},c);
};
prototype.toggleEvent = function(name, state) {
eventTracker[name] = state;
};
});
}([Document.prototype, HTMLElement.prototype, ...]));
example: http://jsfiddle.net/BYSdP/1/
the button gets three click listeners, but if the second button is clicked, the event regulator for "click" is set to false, so none of the events will actually trigger the originally supplied code. Note that this also makes debugging a LOT harder, because you're wrapping handlers in anonymous functions.
event.stopImmediatePropagation() keeps the rest of the handlers from being executed and prevents the
event from bubbling up the DOM tree.
Example:
$( "p" ).click(function( event ) {
event.stopImmediatePropagation();
});
$( "p" ).click(function( event ) {
// This function won't be executed
$( this ).css( "background-color", "#f00" );
});
Source: https://api.jquery.com/event.stopimmediatepropagation/
I am having trouble with multiple clicks being registered in jQuery when only one element has been clicked. I have read some other threads on Stack Overflow to try and work it out but I reckon it is the code I have written. The HTML code is not valid, but that is caused by some HTML 5 and the use of YouTube embed code. Nothing that affects the click.
The jQuery, triggered on document.ready
function setupHorzNav(portalWidth) {
$('.next, .prev').each(function() {
$(this).click(function(e) {
var target = $(this).attr('href');
initiateScroll(target);
console.log("click!");
e.stopPropagation();
e.preventDefault();
return false;
});
});
function initiateScroll(target) {
var position = $(target).offset();
$('html, body').animate({
scrollLeft: position.left
}, 500);
}
}
Example HTML
<nav class="prev-next">
Prev
Next
</nav>
In Firefox one click can log a "Click!" 16 times! Chrome only sees one, but both browsers have shown problems with the above code.
Have I written the code wrongly or is there a bug?
-- Some extra info ------------------------------------------
setupHorzNav is called by another function in my code. I have tested this and have confirmed it is only called once on initial load.
if ( portalWidth >= 1248 ) {
wrapperWidth = newWidth * 4;
setupHorzNav(newWidth);
}
else
{
wrapperWidth = '100%';
}
There are mutiple instances of nav 'prev-next'. All target different anchors. All are within the same html page.
<nav class="prev-next">
Prev
</nav>
Try unbinding the click event like this
$(this).unbind('click').click(function (e) {
});
You don't need .each() for binding event handlers. Try this instead:
$('.next, .prev').click(function(e){
var target = $(this).attr('href');
initiateScroll(target);
console.log("click!");
e.stopPropagation();
e.preventDefault();
return false;
});
EDIT:
I think it is the way you are attaching the event handler from within the setupHorzNav function that is causing it. Change it to attach it only once from say, $(document).ready() or something.
I have managed to get the situation of multiple event handlers by attaching the event handlers from a function that gets called from event handler. The effect is that the number of click event handlers keeps increasing geometrically with each click.
This is the code: (and the jsfiddle demo)
function setupNav() {
$('.next, .prev').each(function () {
$(this).click(function (e) {
setupNav();
var target = $(this).attr('href');
console.log("click!");
e.stopPropagation();
e.preventDefault();
return false;
});
});
}
setupNav();
See how calling the setupNav() function from the click event handler adds multiple eventhandlers (and the click log message) on successive clicks
Since it is not clear from your question whether you are calling the binding function multiple times, a quick and dirty fix would be:
$('.next, .prev').unbind('click').click(function() {
...
});
What you are doing here is unbinding any previously bound event handlers for click and binding afresh.
Are there no other click bindings elsewhere?
Are you loading the page with ajax?
You could also try this:
$('.next, .prev').click(function (e) {
var target = $(this).attr('href');
initiateScroll(target);
console.log("click!");
e.stopPropagation();
e.preventDefault();
return false;
});
I'm not exactly sure how to phrase this, so I couldn't search it. Basically, I have a keydown() bind on $(document). I'd like to show() another div, and have all keydown events be rerouted to this div and prevented from firing off in the document handler. Is this even possible, or would I have to put all my main keybindings on another div and work from there?
e.stopPropagation, or
e.preventDefault (depending on the situation)
Where e is the event.
Ex:
function onKeyDown(e) {
doStuff();
e.preventDefault();
}
e.preventDefault() will prevent the default behaviour of an event. What you need is to use
e.stopPropagation(), so that the event does not bubble up the DOM structure.
$(element).keydown(function(e) {
// do the task
// allow the default behaviour also
e.stopPropagation();
//^. BUT stop the even bubbling up right here
});
e.stopProgation(), can be bit confusing to grasp on the first but I created a demo with click event to explain it.
Hope it helps!!
Try:
$(document).on('keydown', function (evt) {
$('#foo').show().trigger(evt);
});
$('#foo').on('keydown', function (evt) {
console.log(evt);
return false; // this is very important. Without it, you'll get an endless loop.
});
demo: http://jsfiddle.net/Z7vYK/
The only way I can think of to even have a keydown event run on something other than an input or document, is to manually trigger it. You could have a global variable keep track of whether or not your div is showing, then trigger the event on your div accordingly.
Here's one such solution
HTML
Show div
<div id="hiddendiv"></div>
Javascript
var showing = false;
function showdiv()
{
showing = true;
$('#hiddendiv').show(200);
}
// Set up events on page ready
$(function() {
$(document).keydown(function(e) {
// If the div is showing, trigger it's keydown
// event and return
if(showing)
{
$('#hiddendiv').data('keydown_event', e).keydown();
return true;
}
alert('Document keydown! Keycode: ' + e.keyCode);
// Otherwise do the normal keydown stuff...
});
// Keydown for the hidden div
$('#hiddendiv').keydown(function() {
e = $(this).data('keydown_event');
alert('Hiddendiv keydown! Keycode: ' + e.keyCode);
// Make sure to stop propagation, or the events
// will loop for ever
e.stopPropagation();
return false;
});
});
As you can see, the #hiddendiv keydown event is being triggered by the document keydown event. I've also included a slight hack to get the event object to the hidden div using the jQuery data function.
Here's a demonstration of the code: http://jsfiddle.net/Codemonkey/DZecX/1/
I would like to implement the solution like this
How do I detect a click outside an element?
but I'm using another javascript library with $() function already defined
Any suggestions?
This is easy to accomplish. Would be a shame to load the jQuery library just for one feature.
If the other library you're using handles event binding, you could do the same thing in that library. Since you didn't indicate what that other library is, here's a native solution:
Example: http://jsfiddle.net/patrick_dw/wWkJR/1/
window.onload = function() {
// For clicks inside the element
document.getElementById('myElement').onclick = function(e) {
// Make sure the event doesn't bubble from your element
if (e) { e.stopPropagation(); }
else { window.event.cancelBubble = true; }
// Place the code for this element here
alert('this was a click inside');
};
// For clicks elsewhere on the page
document.onclick = function() {
alert('this was a click outside');
};
};
If the $ conflict is your only hold-up, there are ways around that:
http://docs.jquery.com/Using_jQuery_with_Other_Libraries
I also add here the code that stops event bubbling up. Found on quircksmode.org
function doSomething(e) {
if (!e) var e = window.event
// handle event
e.cancelBubble = true;
if (e.stopPropagation) e.stopPropagation();
}