Develop Reference

Freely positionable element (by user) on a web page?

Is this possible? I don't have an example of what I'm asking about obviously, but essentially what I want to do is to have users be able to drag an element around a page, but not have it be restrained to certain positions like drag and drop-able elements in HTML5. The simplest example would be the way windows work on the desktop. I'm sorry if the answer is out there, but I don't know the term to search for.

Sounds like a job for jQueryUI!
Enable draggable functionality on any DOM element. Move the draggable object by clicking on it with the mouse and dragging it anywhere within the viewport.
https://jqueryui.com/draggable/

jQuery Hover Over Image Content Only and Not Alpha

Perhaps the title isn't great, but I had a little trouble with the wording...
Basically, is it possible to have jQuery's hover only fire over the actual content of a png with an alpha channel.
So in the image below;
http://i.imgur.com/3kO7v.png
Only fire on the rectangle and not the alpha channel which make up the rest of the document bounds...
I've tried the obvious $('obj').hover(function(){stuff}) but this fires on the alpha channel too...
The final implementation of this will be for more complex shapes than just a rotated square, so css3 tricks are out for the primary basis, but could be used with a back-up/shim, plus I need to support IE7 and ipad,iphone,ipod....
If there is a CSS2 solution then that would be suitable too. Also any real guidance on this issue is more than welcome.
My backup for this will be to have an empty div, display block and position it over the shape and then use that. This will obviously not be ideal for the less square objects.
Any hits or tips are more than welcome.
Thank you

Yes it is possible depending on the stacking context of your elements. Keep in mind that when you do a focus over any particular element on a page, that you are actually focusing all other elements within the same stacking context.
So what you could do is either stop the event from bubbling up the stack (if the element you want to "hover" is lower in the stack that the elements you want to prevent hover effects on), or specifically put in prevent default for onhover events for all elements in the stacking context except for the one you want to actually get a hover effect.

Create toolbar of images for web app

I'm building a very basic online application where you can take images from a toolbar (or some kind of storage box, since there will eventually be quite a few images) and drag and drop them onto a canvas. I'm new to web development, but I know how to do the drag and drop, I'm just looking for a way to make a toolbar and put images in it. Ideally, I'd like a box with a scrollbar.
This seems like it should be a pretty simple problem. Any help would be much appreciated!

The simplest way I ended up discovering was using
overflow: scroll;
in the CSS div containing the images.

Here's a very good and simple demonstration of the use of drag&drop in HTML5 :
http://html5demos.com/drag
Beware that it's easy to drag links (as in this demo) but it is not possible to drag any images that aren't inside links in IE9.
If you want a totally cross-browser solution, you'll have to revert to old solutions (track mouse down, move and up and set yourself the position of objects).

If you say you know drag&drop and just want a box with a scroll bar then check this: http://jqueryui.com/demos/slider/side-scroll.html

JavaScript library for stretching divs

I need advice. I need to make something like a rich text editor but only for div tags. User can move div, change place of two divs with drag and drop (add gravity), stretch width and height of div with mouse pointer. All divs which can be edited is in one parent div. My question is, because I am new to JavaScript, which library is the best for these kinds of things, has anyone done something similar with some library ?

jQuery UI has the resizable feature for this.

I think it is a good idea to combine methods. For example you can use hte HTML5 features (draggable=true), combined with plain JavaScript and CSS3 (resize: both;).
Have a look at this article for the drag and drop, and at this preview of CSS3's resize.

Simple JavaScript drag and drop witout the help of a library

I am simply looking for a way of using drag and drop without jquery or any other library. If a dragged object is dropped on another element the later element should start an event (in FF - better would be browser independent).
I know that drag and drop for JavaScript was discussed sometimes before but the previous postings didn't help me.
Although I found some examples it is not clear to me if there is a "drop" or "dragdrop" events exist but these things don't work:
<p ondrop='alert("It worked");'>Text</p>
<p ondragdrop='alert("It worked");'>Text</p>
How could this be done?
Many thanks in advance.

I agree with the other answers. A library will save you a lot of time and headache. This is coming from someone who just recently created a drag-and-drop control from scratch.
If you insist though this is what you'll need to do:
Bind a onmousedown event to the div you want to drag (div.onmousedown).
Change the div's position style to absolute (div.style.position = 'absolute')
Begin capturing mouse movement (document.onmousemove).
On mouse move update the div's position (div.style.top|left = '[location]px')
On the div's onmouseup event (or the document's) unbind all the handlers and do any other cleanup (null out position changes, etc).
Some problems a library will probably solve:
While dragging you will select text on the page (looks ugly).
Binding to events is different between browsers.
You have to calculate the size of the element being dragged if you want to show placeholders and to make it not "pop" when you begin dragging the control (since changing to absolute positioning will remove the element from flow).
You will probably want your dragged element to move fluidly so you will have to store some mouse offset when selecting the element or automatically center the element to the mouse.
If you want to drag an item in a list you'll have to write a ton more custom code for that list to accept the dragged item.
You'll have to take into consideration dragging when the window is scrolled and possibly dragging inside other elements that are positioned strangely.

I am simply looking for a way of using drag and drop without jquery or any other library.
I'm sorry, but there are no such thing as simply drag and drop without any library. You can write it all yourself, but that will be a lot of JS to make it work in all browsers.

Hmm. It's probably not that simple that you'd want to do it yourself, but I would look at Peter Michaux's FORK Javascript drag and drop library -- unlike JQuery or all those big libraries, FORK's modules are decoupled from each other, and are simple enough that you could probably look at Peter's source code and figure out the bits you need. (edit: I'd just use FORK.Drag as it's really small: 7.6KB total minified)

While I agree that library is the way to go, the answer you want is onmousedown, onmousemove, onmouseup. You have to handle those three events.
In onmousedown you'd find the target (event.target or similar in different browsers) and set draggedObject = event.target. You'd also start handling the onmousemove event.
Whenever the onmousemove event fired, you'd move the dragged element based on the difference in position since last time the onmousemove event fired.
In the onmouseup event, you'd clear your draggedObject variable and stop handling onmousemove.
It's not very crossbrowser, but it's the core of what you'd need to do for dragging and dropping.