study/02_JavaScript/docment/getElementById.html at master · ItJava/study

43 lines (28 loc) · 914 Bytes

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>GetElementById</title>

    <script type="text/javascript">

        /*
        需求：当用户点击了校验按钮，要获取输入框内容，然后验证是否合法
             校验规则：必须由字母、数字、下划线组成 并且长度是5-12位
         */

        function  onclickFun() {

            var usernameObj=document.getElementById("username");
            var userNameText=usernameObj.value;
            alert(userNameText);

            var patt=/^\w{5,12}$/;

            if(patt.test(userNameText)){
                alert("用户名合法");
            }else {
                alert("用户名不合法!");
            }

        }


    </script>

</head>


<body>

用户名：<input type="text"  id="username" value="汪方晨">
<button onclick="onclickFun()">校验</button>


</body>
</html>

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