Example of fulllscreen functionality written in typescript, that supports multiple browsers.

fullscreen.ts

interface DocumentWithFullscreen extends HTMLDocument {
    mozFullScreenElement?: Element;
    msFullscreenElement?: Element;
    webkitFullscreenElement?: Element;
    msExitFullscreen?: () => void;
    mozCancelFullScreen?: () => void;
    webkitExitFullscreen?: () => void;
}

export function isFullScreen(): boolean {
    const doc = document as DocumentWithFullscreen;
    return !!(doc.fullscreenElement ||
        doc.mozFullScreenElement ||
        doc.webkitFullscreenElement ||
        doc.msFullscreenElement);
}

interface DocumentElementWithFullscreen extends HTMLElement {
    msRequestFullscreen?: () => void;
    mozRequestFullScreen?: () => void;
    webkitRequestFullscreen?: () => void;
}

export function requestFullScreen(element: DocumentElementWithFullscreen) {
    if (element.requestFullscreen) {
        element.requestFullscreen();
    } else if (element.msRequestFullscreen) {
        element.msRequestFullscreen();
    } else if (element.webkitRequestFullscreen) {
        element.webkitRequestFullscreen();
    } else if (element.mozRequestFullScreen){
        element.mozRequestFullScreen();
    }
}

export function exitFullScreen(doc: DocumentWithFullscreen) {
    if (doc.exitFullscreen) {
        doc.exitFullscreen();
    } else if (doc.msExitFullscreen) {
        doc.msExitFullscreen();
    } else if (doc.webkitExitFullscreen) {
        doc.webkitExitFullscreen();
    } else if(doc.mozCancelFullScreen) {
        doc.mozCancelFullScreen();
    }
  }

export function toogleFullScreen(): void {
    if (isFullScreen()) {
        requestFullScreen(document.documentElement);
    }else {
        exitFullScreen(document);
    }
}

Hi bro.

HTMLDocument is deprecated.
please amend it if you have time!

Here is an error in last toogleFullScreen function. Should be:

export function toogleFullScreen(): void {
    if (!isFullScreen()) { // change here
        requestFullScreen(document.documentElement);
    }else {
        exitFullScreen(document);
    }
}

I am using similar approach to handle fullscreen and exitFullScreen request. but it seems that in some browsers even requestFullscreen is available but inside requestFullscreen method, it may throw "fullscreen is not supported" exception as above screenshot from Sentry.
does anyone have idea on how to make the toogleFullScreen() more robust?