JS下兼容性比较好的全屏方法

            toggleFullscreen() {
                const elem = document.querySelector('xxxx'); // 得到你想要全屏的DOM元素
                if (document.webkitCurrentFullScreenElement || document.mozFullScreenElement) {
                    document.webkitExitFullscreen ? document.webkitExitFullscreen() : '';
                    document.mozCancelFullScreen ? document.mozCancelFullScreen() : '';
                } else {
                    elem.mozRequestFullScreen ? elem.mozRequestFullScreen() : '';
                    elem.webkitRequestFullScreen ? elem.webkitRequestFullScreen() : '';
                }
            },

在chrome和firefox下测试通过. chrome 56下, w3c的api其实还没有正规实现, 得加webkit前缀.