What can affect keyboard focus html?

I am trying to put together some accessibility examples for work. One of the checkpoints I need to present is key board focus.

I know how assure controls gain keyboard focus, but I can not f开发者_Python百科igure out what would cause a control to be non-focusable.

The only thing I have had success with is using an invalid index for tabIndex. (TabIndex = "-2"). I would prefer not to use this because this is not really an true example of keyboard trap.

I know how to make a field non focusable. What I am trying to find, is something that causes a field to be non focusable unintentionally.

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• Explicitly setting it to be outside sequential focus navigation by using a negative number (as per HTML 5)
• Calling AnHTMLElementNode.blur() on the target element or an element before it
• Calling AnHTMLElementNode.focus() in such a way that another element gets the focus as a reaction to something that has to be done to reach the target element in sequential navigation
• Using an element that doesn't normally do something (such as a <span>) and adding an onclick event to it.

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Just add disabled:

<input type='text' disabled="disabled" />