HTML contenteditable - Going nifty

So, we have arrived to the third experiment:
Making the selection interact with the user. We will detect if there is any selection and if there is any, we will show a nice little modal box aligned to the selection.

ClientRect object

This is a really simple object, it contains the following attributes on the instance level:

• top
• left
• right
• bottom
• width
• height

Each Range object has its own ClientRect object describing the actual range's dimensions and positions. Cool, huh? So how do we use it? Simple:

//returns a ClientRect object
var clientRect = range.getBoundingClientRect();

Using this object we can simply show up a modal dialog box after some short & basic math using jQuery:

//returns a ClientRect object
var clientRect = range.getBoundingClientRect();
menu.css({
    left: (rect.left +
           (rect.width / 2) -
           (menu.outerWidth(true) / 2)),
                
    top: (rect.top +
          rect.height +
          5)
    })
    .show();

Modifying a selection through Range

Mofiying a selection is not a big deal, you only need to keep in mind some rules:

• Creating a new Range object is done through document.createRange() method.
• The range.setStart() method does NOT accept HTMLElement as a first parameter. You need to pass a TextNode (#text) type node in there.
  Also, Webkit cannot select empty elements (without at least one TextNode)
  Solution: use the Element.firstChild property instead of the Element - in case you only have text inside the element. Otherwise you can write a function which digs down in the Element's children and their children and returns a TextNode.
• range.startContainer and range.endContainer contains the TextNodes where the selection begins and ends. They point to the same TextNode if there is no selection or the selection does not flow out from a TextNode.
• range.startOffset and range.endOffset represent the numbers (positions) where the selection ends. Watch for the positions, they return the "distance" from the beginning of their TextNode, NOT the distance from the parent Element. We used a method to merge these separate TextNodes and another to get the "absolute" position of the caret.

Modifying a selection is quiet simple:

//creating a new range object
var newRange = document.createRange();

//setting up the new range object created at the beginning of the scope
newRange.setStart(theTextNodeYouPreviouslyFound, start);
        
//removeing all range objects and adding the new one
selection.removeAllRanges();
selection.addRange(newRange);

So putting it all together, I have created this small dummy interaction, check it out at this jsfiddle. It is simple, right? =) Just enough for a weekend demonstration. =)

HTML contenteditable - Basics for awesomeness

So, you have already found out the basics of a contenteditable element. Let's focus now on how to work with the Selection and the Range(s) inside.
I will use jQuery for the demostrations because of two reasons:

• I am used with jQuery...
• It is just way easier to delegate your eventHandlers with jQuery since your event will bubble (propagate) up on the DOM (watch out with the context!).

Selection object

The Selection object is a single "static" object of a Window object. You can have more Window objects by adding iframes into your site/app and each frame is going to have its own single Selection object, but no more. You might want to be aware of that.
You can get this object by calling the window.getSelection(); method. That will give you back a reference to the Selection object. Again: the Selection object is single, if you reuse it somewhere else in your code, I recommend storing it in your "parent/owner" scope somewhere. Here's a little experiment with the Selection object:

kldfnlkdnjd
​

​(function () {
    var selection = window.getSelection();
    
    $(document.body)
        .on('click', '[contenteditable]', function () {
            var sel = window.getSelection();
            
            alert(selection === sel);
        });
}());​

As you can see, the selection and the sel references are pointing to the same Selection object so you don't need the sel variable and call the getSelection() method again.
The Selection object provides some methods to edit your selection but you can be more flexible on the Range objects inside the Selection. However, you will need 2 methods for sure, even if you are working with Range objects:

• selection.removeAllRanges()
  Not surprisingly, this will remove all of the Range objects inside.
• selection.addRange(range)
  Adds a Range object to the selection. Weird, huh? =)

A Selection may contain more than one Range, you can achieve that programmatically but as a user I have not found any need for that (yet...).

Range objects

Range objects contain the actual user-selection and it does not really matter if the selection is inside a contenteditable element or somewhere else, it is going to return the selection Range(s) anyway with the proper data about the selection.
I used mostly the range.setStart/setEnd(Node, position) method to set up my selection and place the caret back to the contenteditable when there was a change. These methods take a TextNode as a first argument and a position number.
Also, there are situations when you need a new Range object and throw out the existing one. These cases look something like this:

//the Selection object
var selection = window.getSelection();

//creates a new {Range} object
var newRange = document.createRange();

//this will place the caret at beginning of the 'textNode'
range.setStart(textNode, 0);

//clear up the selection object so Ranges won't collide
selection.removeAllRanges();

//add the new Range object
//this will handle the visul selection also
selection.addRange(newRange);

So these are the really basics of the selections. I think the best way of learning it is doing, so I will come back with examples about "how-to"s and "how-not-to"s soon. =)

Stay tuned, there is a lot more to this. Also, if everything goes as planned we will do some serious interaction going between a simple text editor and the user... ;)

HTML contenteditable - Basics

What is it?

Recently, I have got the opportunity to work with HTMLElements with the attribute contenteditable set (to true if you like it more). This is not over-complicated:

<div contenteditable></div>

<!-- or if you prefer to be more expressive -->

<div contenteditable='true'></div>

Quiet simple, right? =)
It is like a textarea but it is a HTMLDivElement - actually, the prototype object of the object is HTMLDivElement but that is JavaScript/DOM stuff, we don't need that for now.

So the question arises: why would we want to use a contenteditable element instead of a textarea?

Pros:

• Styling is easier
  It is way much easier to align, position, resize, etc. Since you can work with a div (or section or article or span or whatever...) it is way much easier to maintain the element itself.
  Also, you can forget !important rules in your stylesheets.
• (X|HT)ML inside
  You can overwrite the browser's default behaviour and write your own text (or in my case Script/screenplay) editor. Like tinyMCE

Kontras:

• You have just found any enemy. Why? The default behaviour might be/is different in each browser. That just sucks, right? Browser War II... (I am using Webkit [Chrome/Maxthon/Safari])
  So you must write a ridiculously (okay, not that much) massive state-machine which overwrites these default behaviours. (if you want to be the employee of the YEAR at the company, you have good chances now! =D )
• Key events are not firing up on the contenteditable's children elements when working with (X|HT)ML inside
  This is really weird so far, since the mouse events work just fine but the key events... Not a chance in Chrome 21... You might want to give it a try: jsfiddle here.
  So you will have to have a solution for these type of problems. I wrote a small workaround for that eventHandler context issue, it is really basic stuff with jQuery and it is only a first draft but you get the idea. =) And the fiddle is here.

Writing in a contenteditable element

This is the worst part.. You have click on it (place the focus inside), and you're done! =D Just like the textarea, just like that.

Getting the contents of a contenteditable element

You have some ways to do that, I prefer the DOM way for this one since it is very very simple:

//[element] might be a context inside an event handler function refered as 'this'
element.textContent;

You can also use jQuery to achieve the same result:

//[element] might be a context inside an event handler function refered as 'this'
$(element).text();

You just saved 2 function calls with the DOM way but that doesn't really matter.

So, these are the basics of the contenteditable's, quiet simple stuff, just to get you used to it. =)
Let me know if I should write more about how to do some cool stuff with it. Like XML/HTML stuff inside. It can be awesome if you are over the hatred... =D Next »