Difference between onMouseOver and onMouseEnter - javascript

I'm trying to have a simple html table, that highlights a row as a user mouses over it. Unfortunately the css hover item doesn't work for IE. That leaves me to simulate it in Javascript. I can use either onmouseenter or onmouseover.
What is the difference between them, and which one should I use?

Both onmouseenter and onmouseover fire when the mouse enters the boundary of an element. However, onmouseenter doesn't fire again (does not bubble) if the mouse enters a child element within this first element.

Unlike the onmouseover event, the onmouseenter event does not bubble. In other words, the onmouseenter event does not fire when the user moves the mouse pointer over elements contained by the object, whereas onmouseover does fire.
I always use onmouseover. I use onmouseover in the same purpose (highlights a row).

You might spare yourself some coding by just adding :hover support for all elements in IE too:
try csshover.htc

Related

Get mouse coordinates when the mouse is over a disabled element?

When using a global mousemove event attached to the window object, the mouse coordinates are not available when the mouse moves over a disabled element. Disabled elements do not fire any events, presenting a problem.
Part of my application includes a free-transform tool which allows elements to be rotated, scaled, resized and dragged around the viewport (drag & drop). The flow of my app is broken if the mouse is moved over a disabled element while freely transforming an object, because suddenly the mouse coordinates are not available to my objects until the mouse leaves the element, giving a choppy / laggy feel and a poor user experience.
I've tried the readonly attribute instead. However, this is not a viable solution as it is only supported by two elements (input and textarea) source: https://www.w3.org/TR/html4/interact/forms.html#h-17.12 and has different behaviour.
Here's a Fiddle showing the choppy / laggy behaviour: https://jsfiddle.net/rmw9anLs/2/
I understand the element itself doesn't fire any events, but I'm not attaching any events to the disabled element. I would expect the window.mousemove event to fire regardless and don't understand why a disabled element on the page would interrupt a global event listener.
Aside from implementing a custom disabled feature using JavaScript, is there a way to get the mouse coordinates without having to account for the mouse being on top of disabled elements?
You cannot, hence the disabled attribute has no effect, other than making your HTML invalid.
To stop the mouse event working, attach an event handler to the element using event.preventDefault() on it, check for a data-disabled attribute on the element in your existing click handlers or use pointer-events: none in a CSS class which you toggle on/off as needed. Also be aware that pointer-events is not well supported in IE <11
E.g:
https://jsfiddle.net/x4nLu0a5/

Mouseover image interference

Using IE8, i have a mouseover event on a div that contains several images.
When moving over the div the event triggers fine, but the problem is that when the user enters and exists an image, the div mouseover triggers again.
Apperenlty IE8 sees hovering images as leaving the div.
Does anyone know a nice method so the event triggers only once when entering the div and doesn't fire anymore while the user is wihtin the div's borders?
Use mouseenter and mouseleave instead of mouseover and mouseout

What mouse/touch events should I use to cause a div to change color when cursor is dragged over it?

I'd like to know what mouse events I need to use for the task below.
When a cursor is dragged over a div, the div changes color.
By dragged I mean that the mouse button has been clicked once (and not released) somewhere outside the div and then the cursor has been moved over the div (the mouse button has not been released at any time during this process).
The div shouldn't respond to onmouseover. The mouse button needs to have been depressed and then dragged over the div to activate the change in the div.
I'm also wondering if there are any equivalent events for touch devices?
If i understand this right you can do the following:
set a global variable "mousedown" to false
use the "onmousedown" event to set "mousedown" to true
use the "onmouseover" event of your div to fire a function where you first check if mousedown is true and if so make the div visible
use the "onmouseup" event on your page to set "mousedown" to false again
For anything javascript related to touch event you should have a look at Sencha Touch
EDIT: If you want to avoid such frameworks. You should have a look at The HTML5 Specification. There are a couple of new events related to touch devices.
Here is a nice article about it:
http://www.html5rocks.com/en/mobile/touch.html
I'd recommend JQueryUI for this - it has several drag-specific events built-in. The drag event for touch devices is called touchmove

'onmouseover' working unexpectedly in Javascript

I have a div in which there is a link. When a user takes the mouse pointer over the link, I call the basic_nav_mouseover() function which changes the background-image of the parent div. I have also added the function basic_nav_mouseout to the ommouseout attribute of the parent which should set the background-image of the parent div to none when the mouse pointer leaves the div. However, strangely, the function basic_nav_mouseout() is getting called as soon as the mouse pointer in leaving the link in the parent div. Here is a test page : http://spats.in/test/. Look at the links 'about' ,'people','connect' on the top right corner.
Where am I going wrong?
There's a really good explanation of the limitations of the mouseover and mouseout events in the jQuery docs (about half way down that page).
Mouseover and mouseout events trigger when you move the mouse over the bound element, as expected, but they also fire a separate event when you mouse over any inner elements within the parent element - this is obviously undesirable in most circumstances.
Basically, to fix your problem, use the mouseenter and mouseleave events instead.
From a user experience point of view, I'd encourage you to bind both events to the link, so that the special background colour actually indicates that the link is active - I think I'd find the effect you are trying to achieve quite misleading, because the highlighted background would make me think that I can still click the link, even though I cannot..
If you want to keep the visual effect you've current got (with a tall coloured area behind each link), make the link take up the whole box - i.e. 100% of the height and width of the div.
If onmouseover is set on the link, onmouseout should be set on the same element.
onmouseout gets triggered every time a child node is hovered over, you need to check the calling target.
http://www.quirksmode.org/js/events_mouse.html is a good resource.
I'm no javascript expert, but shouldn't you wait with binding the function to the event until the page is fully loaded? So:
window.onload = function(){
$('.item1').bind('mouseleave',basic_nav_mouseout);
};
Also (correct me if I'm wrong) I don't think you have to give the object as an argument in 'basic_nav_mouseout('.item1','red')', you can just use the 'this' keyword. So:
function basic_nav_mouseout(){
this.css('background-image',"none");
}
I don't know anything about the JQuery library though, my only (little) experience is with the Prototype library.

z-index and Javascript events

I have a couple of divs overlaid on each other with differing z-index values.
The default behaviour for browsers seems to be the event bound to the top-most z-index div gets fired. I.e. I have multiple onclicks one for each div but only the top one is fired when the area is clicked.
Is there a way to fire the events attached to all divs no matter what the z-index of each is, so long as the action is 'over' that div without regard to z-index?
The event doesn't actually occur on the element that is obscured by another unless the other element is contained in the first, then it will bubble up. The only way that I can think of to achieve what you want is to go through all of the potential elements and see if any of them contain the point at which the click occurred and trigger a click on that element (if it's not the current one).
If you are using an javaScript framework event bubbling might be included. (ExtJS I know for sure has this kind of event feature.)

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