tabIndex doesn't make a label focusable using Tab key

Solution 1:

Why doesn't tabindex make the label focusable?

Short Answer:

1. Label is focusable.
2. TabIndex won't make any difference.
3. Welcome to the world of browser/agent inconsistencies.

tl;dr;

The label (Ref) element is very much focusable. Its DOM Interface is HTMLLabelElement which derives from HTMLElement (Ref) which in turn implements GlobalEventHandlers (Ref) and hence exposes the focus() method and onfocus event handler.

The reason you are unable to get hold of proper specification / reference document for labels focus behaviour, is because you might have been looking at HTML5 Specs. Interestingly, HTML5 refs do not state anything relating to that, which adds to the confusion.

This is mentioned in the HTML 4.01 Ref here: http://www.w3.org/TR/html401/interact/forms.html#h-17.9.1

Specifically near the end of section 17.9.1 and just before 17.10:

When a LABEL element receives focus, it passes the focus on to its associated control.

Also, elsewhere (I am unable to get hold of that part of the ref) I have read that it depends on the implementing agent. (Don't take my word for that, am not too sure).

However, what it means is that when you focus a label (or a label received a focus), that focus is passed on to its associated labeleable control. This will not result in two different focuses, but one focus on the input (in your case a checkbox). Because of this behaviour, tabindex property cannot play a role.

There is also a test suite by W3C for website accessibility (WAAG) here: http://www.w3.org/WAI/UA/TS/html401/cp0102/0102-ONFOCUS-ONBLUR-LABEL.html which, discusses the implementation of onfocus and onblur for a label. Ideally a keyboard or an assistive technology that emulates the keyboard should implement this. But...

This is where the browser inconsistencies play their role.

This can be demonstrated by this example. Check the following snippet in different browsers. (I have tested it against IE-11, GC-39 and FF-34. All of them behave differently.)

1. Click the button "Focus Label"
2. It should focus the label, then pass the focus and highlight its associated checkbox outline in blue.
3. Chrome-v39 works. IE-v11 it doesn't (somehow html and body do respond to :focus). FF-v34 it works.

Talking about browser inconsistencies, try using the "access key" L. Some browsers will focus the checkbox whereas some will click it i.e. pass the action to it.

Here is a fiddle to test it: http://jsfiddle.net/abhitalks/ff0xds4z/2/

Here is a snippet:

label = $("label").first();
$("#btn").on("click", function() {
    label.focus();
});

* { margin: 8px; }
.highlight { background-color: yellow; }
:focus {
    outline: 2px solid blue;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id="txt" type="text" value="input" /><br />
<label for="chk" accesskey="L">Checkbox: </label>
<input id="chk" type="checkbox" /><br />
<input id="btn" type="button" value="Focus Label" />

Hope that clears up your doubts.

.

Your problem:

Now focussing (sic) on your original problem of not being able to focus a label, because you want to style a checkbox differently by placing an icon kind of thing in its place.

In order to do that, one option for you is to not hide it completely by doing a display:none;. Rather, make it 1x1 pixel and shove it under your icon. This way it will still receive focus naturally and yet be effectively hidden.

For example, if your icons are a checkmark and a cross, then change the position of the checkbox and make the icons out of ::before or ::after pseudo-elements on the label. That will cause the checkbox to still receive focus, and make the icon respond to that. That will give the apparent illusion of the icon taking the focus.

Demo Fiddle: http://jsfiddle.net/abhitalks/v0vxcw77/

Snippet:

div.chkGroup { position: relative; }
input#chk {
    position: absolute;
    width: 1px; height: 1px;
    margin: 0; margin-top: 4px; outline: none;
    border: 1px solid transparent; background-color: transparent;
}
label::before {
    content: '\2714';
    position: relative;
    width: 18px; height: 18px;
    background-color: #fff;
    margin-right: 8px; padding: 2px;
    display: inline-block; 
    border: 1px solid transparent;
}
input#chk:checked + label::before {
    content: '\2716';
}
input#chk:focus + label::before {
    border: 1px solid #00f;
}

<input id="txt" type="text" value="input" /><br /><br />
<div class="chkGroup">
    <input id="chk" type="checkbox" />
    <label for="chk" accesskey="L">Checkbox</label>
</div>

.

Solution 2:

Edit: The following was a misreading of the spec:

Looking that the full specification, you'll see that there is something called tabindex focus flag, which defines if the tabindex attribute will actually make the field "tabbable". The label element is missing from that list of suggested elements.

But then again, so is the span element, so go figure :).

That said, yYou can make the label text focusable by wrapping the whole thing in an another element, or using some JavaScript to force the issue. Unfortunately, wrapping (here in an anchor) can men a fair amount of extra work in CSS and JS to get working like a normal label element.

document.getElementById('checkbox').addEventListener('change', function(event) {
  document.getElementById('val').innerHTML = event.target.checked;
});
document.getElementsByClassName('label')[0].addEventListener('click', function(event) {
  event.target.getElementsByTagName('label')[0].click();
  event.preventDefault();
});
document.getElementsByClassName('label')[0].addEventListener('keypress', function(event) {
  if ((event.key || event.which || event.keyCode) === 32) {
    event.target.getElementsByTagName('label')[0].click();
    event.preventDefault();
  }
});

.label,
.label:visited,
.label:hover,
.label:active {
  text-decoration: none;
  color: black;
}

<div>
  <input type="text" value="input">
</div>
<div>
  <a class="label" href="#">
    <label tabindex="0">
      <input type="checkbox" id="checkbox" style="display:none;">checkbox: <span id="val">false</span>
    </label>
  </a>
</div>
<span tabindex="0">span with tabindex</span>