请老师检查代码

来源：4-11 编程练习

xcn_aaaa

2022-07-11 16:03:49

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>onblur和onfocus</title>
    <style type="text/css">
        .red{
            border:1px solid red;
        }
    </style>
</head>
<body>
    姓名：<input type="text"> <span></span>
    <script type="text/javascript">
        // 补充代码
        var oText = document.querySelector('input');
        var oSpan = document.querySelector('span');
        oText.onfocus = function(){
            oSpan.innerHTML = "请输入您的姓名";
            this.className = '';
        }
        oText.onblur = function(){
            if(oText.value.length==0){
                this.className = 'red'
                oSpan.innerHTML = "用户名不能为空"
            }else{
                oSpan.innerHTML = "";
            }
        }
    </script>

</body>
</html>

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