Files
mkdocs-material/src/assets/javascripts/browser/element/focus/index.ts

73 lines
2.5 KiB
TypeScript

/*
* Copyright (c) 2016-2021 Martin Donath <martin.donath@squidfunk.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
import {
Observable,
debounceTime,
distinctUntilChanged,
fromEvent,
map,
merge,
startWith
} from "rxjs"
import { getActiveElement } from "../_"
/* ----------------------------------------------------------------------------
* Functions
* ------------------------------------------------------------------------- */
/**
* Watch element focus
*
* Previously, this function used `focus` and `blur` events to determine whether
* an element is focused, but this doesn't work if there are focusable elements
* within the elements itself. A better solutions are `focusin` and `focusout`
* events, which bubble up the tree and allow for more fine-grained control.
*
* `debounceTime` is necessary, because when a focus change happens inside an
* element, the observable would first emit `false` and then `true` again.
*
* @param el - Element
*
* @returns Element focus observable
*/
export function watchElementFocus(
el: HTMLElement
): Observable<boolean> {
return merge(
fromEvent(document.body, "focusin"),
fromEvent(document.body, "focusout")
)
.pipe(
debounceTime(1),
map(() => {
const active = getActiveElement()
return typeof active !== "undefined"
? el.contains(active)
: false
}),
startWith(el === getActiveElement()),
distinctUntilChanged()
)
}