handleReset(ev) {
			const tasks = [];

			document.getElementById('maincontent')
				.querySelectorAll('.cbi-map').forEach(map => {
					tasks.push(DOM.callClassMethod(map, 'reset'));
				});

			return Promise.all(tasks);
		}
The handleReset function is invoked when the user clicks
the `Reset` button in the page action footer.

The default implementation should be sufficient for most
views using {@link form#Map form.Map()} based forms - it
will iterate all forms present in the view and invoke
the {@link form#Map#save Map.reset()} method on each form.

Views not using `Map` instances or requiring other special
logic should overwrite `handleReset()` with a custom
implementation.

To disable the `Reset` page footer button, views extending
this base class should overwrite the `handleReset` function
with `null`.

The invocation of this function is wrapped by
`Promise.resolve()` so it may return Promises if needed.

@instance
@memberof LuCI.view
@param {Event} ev
The DOM event that triggered the function.

@returns {*|Promise<*>}
Any return values of this function are discarded, but
passed through `Promise.resolve()` to ensure that any
returned promise runs to completion before the button
is re-enabled.