javascript 表单提交验证：为什么它不显示弹出消息，填写所需的条目，如果表格为空

g6baxovj 于 2023-02-18 发布在 Java

关注(0)|答案(1)|浏览(286)

我正在运行这个问题，我正在点击提交按钮，但它没有显示像“fname，email，message”这样的特定条目是必需的。
我尝试过不同的方法，比如在输入标签中加入“required”属性，但这里也发生了同样的事情。
这是contact.html文件：

<script defer src="script.js"></script>
    <div id="error"></div>
    <div class="con"><div class="he"><h1>Contact Us</h1><br>
    <p>Please feel free to contact us with any questions you may have around our coaching or online        analysis. </p></div>  </div> -->
     <div class="con2"> <div class="form"><form class="form" name="myform" method="GET">
        <label for="fname">First name:</label><br>
        <input type="text" id="fname" name="fname" class="name1">
        <label for="lname"class="n">Last name:</label>
        <input type="text" id="lname" name="lname" class="name2"><br>
        <label for="email">Email:</label><br>
        <input type="text" id="mail2" name="email"class="mail"><br>
        <label for="comment">Message or Comment:</label><br>
         <textarea name="comment" rows="10" cols="30"class="para">
           
            </textarea><br> 
             <button type="submit">Submit</button> 
      </form>
  
</div>
</div>   

</div>

script.Js文件：

const name=document.getElementsByClassName('name1')
const name2=document.getElementsByClassName('name2')
const mail=document.getElementsByClassName('mail')
const para=document.getElementsByClassName('para')
const form=document.getElementsByClassName('form')
const errorElement=document.getElementById('error')

form.addEventListener('submit' , (e)=>{
  let messages = [] if (name1.value == =''|| name1.value == null) {
    messages.push('Name is required')
  }
  if (mail.value == =''|| mail.value == null) {
    messages.push('Mail is required')
  }
  if (para.value == =''|| para.value == null) {
    messages.push('Message is required')
  }
  if (messages.length > 0) {
    e.preventDefault() errorElement.innerText = messages.join(', ')
  }
})

JavaScript

来源：https://stackoverflow.com/questions/75486190/form-submission-validation-why-it-is-not-showing-pop-up-message-that-fill-out-r

1条答案

按热度按时间

ruyhziif1#

请为<form>元素使用id，因为class="form"对于<form>标记和<div>标记都是重复的，<div>标记包裹着<form>。
我已经清理了您的代码，请尝试以下操作：

const form = document.getElementById('form');
const fname = document.getElementById('fname');
const lname = document.getElementById('lname');
const mail = document.getElementById('mail');
const message = document.getElementById('message');
const errorElement = document.getElementById('error');

form.addEventListener('submit', (e) => {
  let messages = [];
  if (fname.value === '' || fname.value == null) {
    messages.push('Name is required');
  }
  if (mail.value === '' || mail.value === null) {
    messages.push('Mail is required');
  }
  if (message.value === '' || message.value === null) {
    messages.push('Message is required');
  }

  if (messages.length > 0) {
    e.preventDefault();
    errorElement.innerText = messages.join(', ');
  }
})

<div id="error"></div>

 <div class="con2">
   <form id="form" name="myform" method="GET">
     <label for="fname">First name:</label><br>
     <input type="text" id="fname" name="fname" class="name1">
     
     <label for="lname" class="n">Last name:</label>
     <input type="text" id="lname" name="lname" class="name2"><br>
     
     <label for="email">Email:</label><br>
     <input type="text" id="mail" name="email" class="mail"><br>
     
     <label for="comment">Message or Comment:</label><br>
     <textarea name="comment" rows="10" cols="30" id="message"></textarea><br>
     
     <button type="submit">Submit</button>
   </form>
 </div>

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javascript 表单提交验证：为什么它不显示弹出消息，填写所需的条目，如果表格为空

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