The difference between functions onclick and onsubmit

The difference between functions onclick and onsubmit

onsubmit can only be used on forms and will be triggered before submitting the form. onclick is used by controls such as buttons to trigger click events.

Before submitting the form, data verification is generally performed. You can choose to verify in onclick on the submit button or in onsubmit.

But onclick is triggered earlier than onsubmit

1. The user clicks the button——>

2. The onclick event is triggered——>

3. onclick returns true or is not processed onclick --->

4. Triggers onsubmit event --->

5. onsubmit is not processed or returns true --->

6. Submit the form.

 onsubmit处理函数返回false，onclick函数返回false，都不会引起表单提交。

---

The first type: onsubmit

code block

<script language="javascript">
   function CheckPost ()
   {
      if (addForm.user.value == "")
      {
          alert("请填写用户名！");
          addForm.username.focus();          
          return false;
      }     
      if (addForm.title.value.length < 5)
     {
          alert("标题不能少于5个字符！");
          addForm.title.focus();          
          return false;
     }     return true;
   }
   </script>
   
   <form action="test.php" method="post" name="addForm"  onsubmit="return CheckPost();">
     <p>用户:<input type="text" size="10" name="user" maxlength="20"/></p>
     <p>标题:<input type="text" name="title" maxlength="50"/></p>
     <p>内容:<textarea name="content" rows="8" cols="30"></textarea></p>
     <p>
           <input type="submit" name="submit" value="发表留言"/>
     </p>
   </form>

The second type: onclick

<script language="javascript">
 2     function SendForm () 
 3     {
 4         if(CheckPost()) 
 5         { 
 6             document.addForm.submit(); 
 7         } 
 8     } 
 9 
 10     function CheckPost () 
 11     {
 12          if (addForm.user.value == "") 
 13          {
 14                alert("请填写用户名！");
 15                addForm.username.focus();
 16                return false;
 17          }
 18          if (addForm.title.value.length < 5) 
 19          {
 20                alert("标题不能少于5个字符！");
 21                addForm.title.focus();
 22                return false;
 23          }
 24          return true;
 25     }
 26 </script>
 27 
 28 <form action="test.php" method="post" name="addForm">
 29      <p>用户:<input type="text" size="10" name="user" maxlength="20"/></p>
 30      <p>标题:<input type="text" name="title" maxlength="50"/></p>
 31      <p>内容:<textarea name="content" rows="8" cols="30"></textarea></p>
 32      <p><input type="button" name="submit" value="发表留言" onclick="SendForm();"/></p>
 33 </form>

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