// 全屏
function fullScreen() {
    var element = document.documentElement;
    if (element.requestFullscreen) {
        element.requestFullscreen();
    } else if (element.msRequestFullscreen) {
        element.msRequestFullscreen();
    } else if (element.mozRequestFullScreen) {
        element.mozRequestFullScreen();
    } else if (element.webkitRequestFullscreen) {
        element.webkitRequestFullscreen();
    }
}
// 退出全屏
function exitFullscreen() {
    if (document.exitFullscreen) {
        document.exitFullscreen();
    } else if (document.msExitFullscreen) {
        document.msExitFullscreen();
    } else if (document.mozCancelFullScreen) {
        document.mozCancelFullScreen();
    } else if (document.webkitExitFullscreen) {
        document.webkitExitFullscreen();
    }
}