Detailed explanation on the submission usage of form form submit and button in html-HTML Tutorial-php.cn

Detailed explanation on the submission usage of form form submit and button in html

黄舟

Release： 2018-05-25 11:27:55

Original

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1. When the entered username and password are empty, judgment is required. At this time, verification of username and password is used. This needs to be written on the front-end page of jsp; there are two methods, one is to submit using submit. One is to submit using button.
Method one:
Insert a js method in the head of the jsp front-end page:

function checkUser(){
   var result = document.getElementById("userid").value;
   var password = document.getElementById("userpassid").value;
   if(result == ""  ){
     alert("用户名不能为空");
     return false;
   }
   if(password == ""  ){
    alert("密码不能为空");
     return false;
   }else{
   return true;
   }
}

Copy after login

Write it like this in the form:

<form id="formid"  name= "myform" method = &#39;post&#39;  action = &#39;user_login_submit.action&#39;
onsubmit = "return checkUser();
" >
            <table width="100%" border="0">
              <tr>
                <td width="60" height="40" align="right">用户名 </td>
                <td><input type="text" value="" class="text2" name = "username" id = "userid"/></td>
              </tr>
              <tr>
                <td width="60" height="40" align="right">密  码 </td>
                <td><input type="password" value="" class="text2" name = "userpass" id = "userpassid"/></td>
              </tr>
              <tr>
                <td width="60" height="40" align="right"> </td>
                <td><p class="c4">
                    <input type="submit" value="" class="btn2"  />

Copy after login

Method two:

function checkUser(){
   var result = document.getElementById("userid").value;
   var password = document.getElementById("passid").value;
   if(result == ""  ){
     alert("用户名不能为空");
     return false;
   }
   if(password == ""  ){
    alert("密码不能为空");
     return false;
   }
  document.getElementById("formid").submit();
}

Copy after login

For the form, you need to write the id

<form id="formid" method = &#39;post&#39;  action = &#39;user_login_submit.action&#39;  >

Copy after login

The button button is written as follows:

<input type="button" value="" class="btn2" onclick = "checkUser();" />

Copy after login

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