获取屏幕可视区域

 client: function() {
            if(window.innerWidth !== null){ // 最新的浏览器
                return {
                    "width": window.innerWidth,
                    "height": window.innerHeight
                }
            }else if(document.compatMode === 'CSS1Compat'){ // W3C
                return {
                    "width": document.documentElement.clientWidth,
                    "height": document.documentElement.clientHeight
                }
            }
            return {
                "width": document.body.clientWidth,
                "height": document.body.clientHeight
            }
        }

console.log(window.innerWidth, window.innerHeight);
console.log(document.documentElement.clientWidth, document.documentElement.clientHeight);
console.log(document.body.clientWidth, document.body.clientHeight);