Getting keyboard-focusable elements

If you create JavaScript widgets, one of the key parts to accessibility is managing focus.

To manage focus, you need to find keyboard-focusable elements.

When you know the contents

It’s easy to find keyboard-focusable elements if you know the contents of the element beforehand.

For example, I know the focusable elements in this modal are <input> and <button>.

I can get the focusable elements with querySelectorAll.

const focusableElements = [...modal.querySelectorAll('input, button')]

When you don’t know the contents

It’s harder to find keyboard-focusable elements if you don’t know the content beforehand.

After some research, I realised you could only focus on these elements with a keyboard:

1. <a> with the href attribute
2. <button>
3. <input>
4. <textarea>
5. <select>
6. <details>
7. Elements with tabindex set to 0
8. Elements with tabindex set to a positive number

We can get all keyboard-focusable elements with the following querySelectorAll. It looks a little complicated, but there’s no other way to include everything:

const keyboardfocusableElements = document.querySelectorAll(
  'a[href], button, input, textarea, select, details, [tabindex]:not([tabindex="-1"])',
)

Some elements (like button) can be disabled. Disabled elements are not focusable.

In some libraries form fields are hidden visually (CSS) and for At (aria-hidden="true") and replaced by better looking components that should be accessible.

We can remove these elements with filter.

const keyboardfocusableElements = [
  ...document.querySelectorAll(
    'a[href], button, input, textarea, select, details, [tabindex]:not([tabindex="-1"])',
  ),
].filter(el => !el.hasAttribute('disabled') && !el.getAttribute('aria-hidden'))

Turning it into a function

This querySelectorAll code is hard to read. We can put the entire thing into a function to make it more understandable.

/**
 * Gets keyboard-focusable elements within a specified element
 * @param {HTMLElement} [element=document] element
 * @returns {Array}
 */
function getKeyboardFocusableElements(element = document) {
  return [
    ...element.querySelectorAll(
      'a[href], button, input, textarea, select, details,[tabindex]:not([tabindex="-1"])',
    ),
  ].filter(
    el => !el.hasAttribute('disabled') && !el.getAttribute('aria-hidden'),
  )
}

Update: Lauren contacted me and asked about display:none. Certainly these elements won’t be focusable so we have to filter them out too. I also included a list of other elements that I never thought about before — embed, object, iframe, etc.

I updated the code in my Github repository — you can get the updated code if you sign up below.