Javascript 未捕获类型错误：无法读取属性'；价值'；在HTMLInputElement.onclick的signUpValidate（fhe.js:26）处为null
我正在尝试让用户输入他们的注册信息。我遇到了一个错误，看起来我知道错误是什么，但我不知道如何修复它。请找人帮忙 未捕获的TypeError:无法在HTMLInputElement.onclick的signUpValidate（fhe.js:26）处读取null的属性“value” HTML代码：Javascript 未捕获类型错误：无法读取属性'；价值'；在HTMLInputElement.onclick的signUpValidate（fhe.js:26）处为null,javascript,html,Javascript,Html,我正在尝试让用户输入他们的注册信息。我遇到了一个错误，看起来我知道错误是什么，但我不知道如何修复它。请找人帮忙 未捕获的TypeError:无法在HTMLInputElement.onclick的signUpValidate（fhe.js:26）处读取null的属性“value” HTML代码： <!DOCTYPE html> <html lang="en">`enter code here` <head> <script type="text/
<!DOCTYPE html>
<html lang="en">`enter code here`
<head>
<script type="text/javascript" src="fhe.js"></script>
<link rel="stylesheet" href="fheCss.css"/>
<meta charset="UTF-8">
<title>Sign Up Page</title>
<h1>Family Home Evening</h1>
<h3>Sign Up</h3>
</head>
<body class="backgroundPic">
<form class="mySignUpForm">
<input type="text" placeholder="First Name" name="firstName" required/><br><br>
<input type="text" placeholder="Last Name" name="lastName" required/><br><br>
<input type="text" placeholder="Username" name="signUpUserName" pattern="^[a-zA-Z][a-zA-Z0-9-_\.]{8,20}$" required/><br><br>
<input type="text" placeholder="Password" name="signUpPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
<input type="text" placeholder="Verify Password" name="signUpVerPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
<input type="button" value="Sign up" id="signup" onclick="signUpValidate()"/><br><br>
<a href="login.html">Back to Login</a><br><br>
</form>
<h4>Username: Username must be between 8 to 20 character<br><br>
Password: Password must contain 1 uppercase, lowercase and number</h4><br><br>
</body>
</html>
您正在使用
document.getElementByIddocument.getElementByIddocument.getElementById（）ID<input type="text" id="firstName" placeholder="First Name" name="firstName" required/><br><br>
<input type="text" id="lastName" placeholder="Last Name" name="lastName" required/><br><br>
<input type="text" id="signUpUserName" placeholder="Username" name="signUpUserName" pattern="^[a-zA-Z][a-zA-Z0-9-_\.]{8,20}$" required/><br><br>
<input type="text" id="signUpPassword" placeholder="Password" name="signUpPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
<input type="text" id="signUpVerPassword" placeholder="Verify Password" name="signUpVerPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
document.getElementById（）id<input type="text" id="firstName" placeholder="First Name" name="firstName" required/><br><br>
<input type="text" id="lastName" placeholder="Last Name" name="lastName" required/><br><br>
<input type="text" id="signUpUserName" placeholder="Username" name="signUpUserName" pattern="^[a-zA-Z][a-zA-Z0-9-_\.]{8,20}$" required/><br><br>
<input type="text" id="signUpPassword" placeholder="Password" name="signUpPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
<input type="text" id="signUpVerPassword" placeholder="Verify Password" name="signUpVerPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
getElementById<!DOCTYPE html>
<html lang="en">`enter code here`
<head>
<script type="text/javascript" src="fhe.js"></script>
<link rel="stylesheet" href="fheCss.css"/>
<meta charset="UTF-8">
<title>Sign Up Page</title>
<h1>Family Home Evening</h1>
<h3>Sign Up</h3>
</head>
<body class="backgroundPic">
<form class="mySignUpForm">
<input type="text" placeholder="First Name" name="firstName" id="firstName" required/><br><br>
<input type="text" placeholder="Last Name" name="lastName" id="lastName" required/><br><br>
<input type="text" placeholder="Username" name="signUpUserName" id="signUpPassword" pattern="^[a-zA-Z][a-zA-Z0-9-_\.]{8,20}$" required/><br><br>
<input type="text" placeholder="Password" name="signUpPassword" id="signUpPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
<input type="text" placeholder="Verify Password" name="signUpVerPassword" id="signUpVerPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
<input type="button" value="Sign up" id="signup" onclick="signUpValidate()"/><br><br>
<a href="login.html">Back to Login</a><br><br>
</form>
<h4>Username: Username must be between 8 to 20 character<br><br>
Password: Password must contain 1 uppercase, lowercase and number</h4><br><br>
</body>
</html>
`在这里输入代码`
注册页面
家庭之夜
注册
用户名：用户名必须在8到20个字符之间
密码：密码必须包含1个大写、小写和数字
getElementById<!DOCTYPE html>
<html lang="en">`enter code here`
<head>
<script type="text/javascript" src="fhe.js"></script>
<link rel="stylesheet" href="fheCss.css"/>
<meta charset="UTF-8">
<title>Sign Up Page</title>
<h1>Family Home Evening</h1>
<h3>Sign Up</h3>
</head>
<body class="backgroundPic">
<form class="mySignUpForm">
<input type="text" placeholder="First Name" name="firstName" id="firstName" required/><br><br>
<input type="text" placeholder="Last Name" name="lastName" id="lastName" required/><br><br>
<input type="text" placeholder="Username" name="signUpUserName" id="signUpPassword" pattern="^[a-zA-Z][a-zA-Z0-9-_\.]{8,20}$" required/><br><br>
<input type="text" placeholder="Password" name="signUpPassword" id="signUpPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
<input type="text" placeholder="Verify Password" name="signUpVerPassword" id="signUpVerPassword" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required/><br><br>
<input type="button" value="Sign up" id="signup" onclick="signUpValidate()"/><br><br>
<a href="login.html">Back to Login</a><br><br>
</form>
<h4>Username: Username must be between 8 to 20 character<br><br>
Password: Password must contain 1 uppercase, lowercase and number</h4><br><br>
</body>
</html>
`在这里输入代码`
注册页面
家庭之夜
注册
用户名：用户名必须在8到20个字符之间
密码：密码必须包含1个大写、小写和数字