尝试在 javascript 中验证用户名和密码，但没有收到警报和所需的 output

Question

please check the code请检查代码

 function validate() { var name = document.getElementById("name"); var pwd = document.getElementById("pwd"); if (name == null || name == "") { alert("Name can't be blank"); return false; } else if (pwd.length < 6) { alert("Password must be at least 6 characters long."); return false; } }

 <form> username: <input type="text" id="name"></input> <br> password: <input type="password" id="pwd"></input> <br> <button onclick="validate()">Submit</button> </form>

Answer 1

 function validate() { var name = document.getElementById("name").value; var pwd = document.getElementById("pwd").value; if (name === null || name === "") { alert("Name can't be blank"); return false; } else if (pwd.length < 6) { alert("Password must be at least 6 characters long."); return false; } }

 <form> username: <input type="text" id="name"></input> <br> password: <input type="password" id="pwd"></input> <br> <button onclick="validate()">Submit</button> </form>

Answer 2

There's a much easier way to do what you are trying to do.有一种更简单的方法可以做你想做的事情。 You can use the native properties of form to your advantage:您可以使用form的原生属性来发挥自己的优势：

 <form> Username: <input type="text" minlength="2" required> <br> Password: <input type="password" minlength="6" required> <br> <button type="submit">Submit</button> </form>

Answer 3

HTML elements should be before javascript, like this: HTML 元素应在 javascript 之前，如下所示：

<!DOCTYPE html>
<html>
<body>

<form>
  username: <input type="text" id="name"></input>
  <br>
  password: <input type="password" id="pwd"></input>
  <br>
  <button onclick="validate()">Submit</button>
</form>

<script>
function validate() {

  var name = document.getElementById("name").value;
  var pwd = document.getElementById("pwd").value;
  if (name == null || name == "") {
    alert("Name can't be blank");
    return false;
  } else if (pwd.length < 6) {
    alert("Password must be at least 6 characters long.");
    return false;
  }
}
</script>

</body>
</html>

You haven't provided the full code, so we can't really help you.您还没有提供完整的代码，所以我们无法真正帮助您。 As far as i can see you didn't make the alert for succesful validation.据我所知，您没有发出成功验证的警报。
You need to get the value, so you need to add.value to the getElement functions.您需要获取该值，因此您需要将 add.value 添加到 getElement 函数中。

尝试在 javascript 中验证用户名和密码，但没有收到警报和所需的 output

问题描述

3 个解决方案

解决方案1
4 2021-05-12 15:00:59

解决方案2
2 2021-05-12 15:07:39

解决方案3
-1 2021-05-12 15:05:53

尝试在 javascript 中验证用户名和密码，但没有收到警报和所需的 output

问题描述

3 个解决方案

解决方案1 4 2021-05-12 15:00:59

解决方案2 2 2021-05-12 15:07:39

解决方案3 -1 2021-05-12 15:05:53

解决方案1
4 2021-05-12 15:00:59

解决方案2
2 2021-05-12 15:07:39

解决方案3
-1 2021-05-12 15:05:53