切换标题 - 掘金

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>我是个大笨蛋</title>
</head>
<body>
    <p>我是程锴大爹</p>

    <script>
        let title =document.querySelector('title');
        //onfocus获取焦点
        window.onfocus=function(){
        
            zz= setTimeout(() => {
                title.innerHTML='我是个大笨蛋'
            }, 3000);
            title.innerHTML='大爷，里面坐';
        }
      //onblur 失去焦点
        window.onblur=function(){
            clearTimeout(zz)
            title.innerHTML='客官下次再来';
        }
       let zz= setTimeout(() => {
                title.innerHTML='我是个大笨蛋'
            }, 3000);
            
    </script>
</body>
</html>