screenFull —— 设置全屏

1.下载 yarn add screenfull
2.给按钮添加点击事件 
    onclick = {this.screenFull}
    screenFull = () => {
        if(screenfull.isEnable){
            screenfull.toggle();  //切换全屏
        }    
   }
3.组件挂载时，绑定全屏事件
   screenfull.on('change',this.change)
   change = ()=>{
       this.setState({isScreenFull:!this.StaticRange.isScreenFull})
   }
4.组件卸载时，解绑事件
   screenfull.off('change',this.change)