全屏显示

var docElm = document.documentElement;
//W3C  
if (docElm.requestFullscreen) {  
    docElm.requestFullscreen();  
}
//FireFox  
else if (docElm.mozRequestFullScreen) {  
    docElm.mozRequestFullScreen();  
}
//Chrome等  
else if (docElm.webkitRequestFullScreen) {  
    docElm.webkitRequestFullScreen();  
}
//IE11
else if (elem.msRequestFullscreen) {
  elem.msRequestFullscreen();
}

退出全屏

if (document.exitFullscreen) {  
    document.exitFullscreen();  
}  
else if (document.mozCancelFullScreen) {  
    document.mozCancelFullScreen();  
}  
else if (document.webkitCancelFullScreen) {  
    document.webkitCancelFullScreen();  
}
else if (document.msExitFullscreen) {
      document.msExitFullscreen();
}

事件监听

document.addEventListener("fullscreenchange", function () {  
    fullscreenState.innerHTML = (document.fullscreen)? "" : "not ";}, false);  
   
document.addEventListener("mozfullscreenchange", function () {  
    fullscreenState.innerHTML = (document.mozFullScreen)? "" : "not ";}, false);  
   
document.addEventListener("webkitfullscreenchange", function () {  
    fullscreenState.innerHTML = (document.webkitIsFullScreen)? "" : "not ";}, false);
document.addEventListener("msfullscreenchange", function () {
    fullscreenState.innerHTML = (document.msFullscreenElement)? "" : "not ";}, false);

原文链接：https://blog.csdn.net/yuntian1995/article/details/78356463