AnchorDisabler.coffee - disable links once and for all with a.disabled or the disabled attribute

AnchorDisabler

class AnchorDisabler
  ###
    This provides for multiple levels of defense so that Anchors marked as disable actually behave as such.
    Using this approach, you get an anchor that you cannot:
      - click
      - tab to and hit return
      - tabbing to it will move focus to the next focusable element
      - it is aware if the anchor is subsequently enabled


    1.  Include this css, as it is the first line of defense.  This assumes the selector you use is 'a.disabled'
        a.disabled {
          pointer-events: none;
          cursor: default;
        }

     2. Next, instantiate this class such as (with optional selector):
        $ ->
          new AnchorDisabler()

  ###
  constructor: (selector = 'a.disabled') ->
    $(selector).click(@onClick).keyup(@onKeyup).focus(@onFocus)

  isStillDisabled: (ev) =>
    ### since disabled can be a class or an attribute, and it can be dynamically removed, always recheck on a watched event ###
    target = $(ev.target)
    return true if target.hasClass('disabled')
    return true if target.attr('disabled') is 'disabled'
    return false

  onFocus: (ev) =>
    ### if an attempt is made to focus on a disabled element, just move it along to the next focusable one. ###
    return unless @isStillDisabled(ev)

    focusables = $(':focusable')
    return unless focusables

    current = focusables.index(ev.target)
    next = (if focusables.eq(current + 1).length then focusables.eq(current + 1) else focusables.eq(0))

    next.focus() if next


  onClick: (ev) =>
    # disabled could be dynamically removed
    return unless @isStillDisabled(ev)

    ev.preventDefault()
    return false

  onKeyup: (ev) =>

    # 13 is the js key code for Enter, we are only interested in disabling that so get out fast
    code = ev.keyCode or ev.which
    return unless code is 13

    # disabled could be dynamically removed
    return unless @isStillDisabled(ev)

    ev.preventDefault()
    return false

how would I translate this in vanilla javascript?