Put action after state with default value in reducer will cause jshint to complain

[anianj]

JSHint will report:
Regular parameters should not come after default parameters. W138

[gaearon]

Well, we don’t agree with this particular rule. You can either disable it, or not use optional parameters and write something like

function counter(state, action) {
  if (typeof state === 'undefined') {
    return 0
  }

  switch (action.type) {
    // ...
  }
}