Question

我的所有var语句都使用标识符：var identifier = document.getElementById（“somename”）;那么为什么我会得到一个null错误。我在javascript运行器中运行此代码并获得null错误消息。在我的浏览器Firefox和Chrome中，我没有收到任何错误或警告。当我在浏览器中运行代码并单击按钮以激活事件处理程序时，表单将清除。无论如何，它不会去服务器。这只是练习。我正在学习javascript和动态HTML课程。如果有人关心我的代码并告诉我我做错了什么我会很感激。必须有一些我没有做对的事情。这是脚本：

 window.onload = function(){
 var fname = document.getElementById("fname").value;
 var lname = document.getElementById("lname").value;
 var loginName = document.getElementById("uname").value;

 var myEmail = document.getElementById("email").value;

 var pass1 = document.getElementById("password1").value;
 var pass2 = document.getElementById("password2").value;
 if(document.getElementById("uname").value == ""){
    return false;
    alert("Your user name can't be blank.");
  };

 if(pass1.value !== pass2.value){
    get.documentElementById("signin").value.disabled = true;
    return false;
    alert("Please retype your password.");
 }else if(pass1.value === pass2.value){
 alert("Welcome!");
 };
 };
 HTML
 <body>
 <form action = "" name = "form" method = "Post">
 <label for="fname">First Name:</label><input type = "text" id =  "fname"required></input>

 <label for="lname">Last Name:</label><input type = "text" id = "lname"   required></input>

 <label for="uname">User Name:</label><input type = "text" id = "uname" required></input><br/>

 <label for="password1">Password:</label><input type = "password" id = "password1"required ></input><br/>

 <label for="password2">Verify Password:</label><input type = "password" id = "password2"required ></input><br/>

 <label for="email">Email Address:</label><input type = "email" id = "email" required></input><br/>

 <button type = "submit"id = "signin" onclick = "function()">Submit</button>
</form>
 <script src="signUp.js"></script>
 </body>

Answer 1

我为你清理了你的代码。有几个地方你有错误（例如，输入pass1.value而不仅仅是pass1。这应该有效，但当然需要时间来研究它，看看我改变了什么并理解为什么。{{3请注意，你永远不应该期望这种类型的代码在你引用的“runners”中运行;这里的代码明确引用了DOM中的特定元素，这些元素是跑步者不会拥有的。像JSFiddle这样的网站更适合这种事情，因为你也可以将HTML放入其中。）

var submitForm = function () {
    var fname = document.getElementById("fname").value;
    var lname = document.getElementById("lname").value;
    var loginName = document.getElementById("uname").value;
    var myEmail = document.getElementById("email").value;
    var pass1 = document.getElementById("password1").value;
    var pass2 = document.getElementById("password2").value;
    console.log(pass1, pass2);
    if (document.getElementById("uname").value == "") {
        alert("Your user name can't be blank.");
        return false;
    }

    if (pass1 !== pass2) {
        document.getElementById("signin").value.disabled = true;
        alert("Please retype your password.");
        return false;
    } else if (pass1 === pass2) {
        alert("Welcome!");
    }
};

 <body>
 <form action="" name="form" method="POST">
 <label for="fname">First Name:</label><input type ="text" id = "fname" required></input>

 <label for="lname">Last Name:</label><input type = "text" id = "lname" required></input>

 <label for="uname">User Name:</label><input type ="text" id ="uname" required></input><br/>

 <label for="password1">Password:</label><input type="password" id="password1" required></input><br/>

 <label for="password2">Verify Password:</label><input type="password" id="password2" required ></input><br/>

 <label for="email">Email Address:</label><input type="email" id="email" required></input><br/>

 <button type="submit" id="signin" onclick="submitForm()">Submit</button>
</form>
</body>

TypeError：document.getElementById（...）;是空的javascript

1 个答案: