Helper method for finding an ancestor element.

_closest.js

/*
  This method works similarly
  to jQuery's `closest` method.

  ```
  $('.foo').closest('.bar')
  ```

  Except, instead of returning an
  element, it executes a function.

  Used like this…

  ```
  const el = closest(e.target, function (el) {
    // Get class name.
    const c = el.className

    // Check validity.
    if (
      typeof c === 'string' &&
      c.match('foo-class__here')
    ) {
      return el
    }
  })
  ```
*/
function closest (el, fn) {
  // Exit.
  if (el === document.documentElement) {
    return
  }

  // Proceed.
  return el && (
    fn(el)
    ? el
    : closest(el.parentNode, fn)
  )
}

// Export.
export default closest