浏览器各事件

1、浏览器切换事件 visibilitychange

document.addEventListener('visibilitychange', () => { 
    if(document.visibilityState === "hidden") {
       document.title = "喂，你人呢？"
    }
    if(document.visibilityState === "visible") {
       document.title = "哎呀，你回来啦！"
    }
})

2、浏览器关闭事件 beforeunload 

window.addEventListener('beforeunload',()=>{
    console.log('啊？你要走了啊！')
})

 3、浏览器刷新事件 onload

window.addEventListener('onload',()=>{
    console.log('刷一刷！浪一浪！')
})