How to keep focus within modal dialog?

Question

I\'m developing an app with Angular and Semantic-UI. The app should be accessible, this means it should be compliant with WCAG 2.0. To reach this p

Answer 1

Don't use any solution requiring you to look up "tabbable" elements. Instead, use keydown and either click events or a backdrop in an effective manor.

(Angular1)

See Asheesh Kumar's answer at https://stackoverflow.com/a/31292097/1754995 for something similar to what I am going for below.

(Angular2-x, I haven't done Angular1 in a while)

Say you have 3 components: BackdropComponent, ModalComponent (has an input), and AppComponent (has an input, the BackdropComponent, and the ModalComponent). You display BackdropComponent and ModalComponent with the correct z-index, both are currently displayed/visible.

What you need to do is have a general window.keydown event with preventDefault() to stop all tabbing when the backdrop/modal component is displayed. I recommend you put that on a BackdropComponent. Then you need a keydown.tab event with stopPropagation() to handle tabbing for the ModalComponent. Both the window.keydown and keydown.tab could probably be in the ModalComponent but there is purpose in a BackdropComponent further than just modals.

This should prevent clicking and tabbing to the AppComponent input and only click or tab to the ModalComponent input [and browser stuffs] when the modal is shown.

If you don't want to use a backdrop to prevent clicking, you can use use click events similarly to the keydown events described above.

Backdrop Component:

@Component({
selector: 'my-backdrop',
host: {
    'tabindex': '-1',
    '(window:keydown)': 'preventTabbing($event)'
},
...
})
export class BackdropComponent {
    ...
    private preventTabbing(event: KeyboardEvent) {
        if (event.keyCode === 9) { // && backdrop shown?
            event.preventDefault();
        }
    }
    ...
}

Modal Component:

@Component({
selector: 'my-modal',
host: {
    'tabindex': '-1',
    '(keydown.tab)': 'onTab($event)'
},
...
})
export class ModalComponent {
    ...
    private onTab(event: KeyboardEvent) {
        event.stopPropagation();
    }
    ...
}