Two ways to submit form forms, submit and button usage

1. When you enter the user name and password is empty, you need to judge. This is the use of verifying the user name and password, this needs to be written on the front page of the JSP, there are two ways, one is to submit with submit. One is to submit with a button.
Method One:

Insert a JS method in the header of the front page of the JSP:

function CheckUser () {
var result = document.getElementById ("userid"). Value;
var password = document.getElementById ("Userpassid"). Value;
if (result = = "") {
Alert ("User name cannot be empty");
return false;
}
if (password = = "") {
Alert ("Password cannot be null");
return false;
}else{
return true;
}
}

Write this in the form form:

<form id= "Formid" Name= "myform" method = ' post ' action = ' user_login_submit.action ' onsubmit = ' return CheckUser (); " >
<table width= "100%" border= "0" >
<tr>
&LT;TD width= "height=" align= "right" > User name &nbsp;</td>
<td><input type= "text" value= "" class= "text2" name = "username" id = "userid"/></td>
</tr>
<tr>
&LT;TD width= "height=" align= "right" > Secret &nbsp;&nbsp; code &nbsp;</td>
<td><input type= "password" value= "" class= "text2" name = "Userpass" id = "Userpassid"/></td>
</tr>
<tr>
&LT;TD width= "height=" align= "right" >&nbsp;</td>
<td><div class= "C4" >
<input type= "Submit" value= "class=" btn2 "/>


Method Two:

function CheckUser () {
var result = document.getElementById ("userid"). Value;
var password = document.getElementById ("Passid"). Value;

if (result = = "") {
Alert ("User name cannot be empty");
return false;
}
if (password = = "") {
Alert ("Password cannot be null");
return false;
}
document.getElementById ("Formid"). Submit ();
}

Form form, need to write ID
<form id= "Formid" method = ' post ' action = ' user_login_submit.action ' >

The button buttons are written as follows:

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