jquery under the Submit, click the button does not respond, the Post method does not perform JSON mode in the form form without effect

When using jquery submission:

(1)

<button id= "Login" > Login </button>

$ (). Ready (function () {
  $ ("#login")
  	. button ()
  	. Click (function () {
        	//alert ("username" +$ ("#userName "). Val ());
  		$.post ("
  	        	checklogin.action",
  			{"username": $ ("#username"). Val (), "Password": $ ("#password"). Val ()},
  			function (data) {
  				//alert (DATA.SUC)
  				if (data.suc) {
  				        window.location.href= "userlist.action";
  			        } else {
  					$ ("#error_message"). HTML ("* The username or password is incorrect.");
  				}
  			,
  			"JSON"		
  	);
 });

(2)

<input type= "image" Src= "Images/btn_login.png" onclick= "Javascript:submitform ()" id= "Btn_log" width= "" height= " /> "

function SubmitForm () {
  if ($ ("#userName"). val () = "")
  	$ ("#error_message"). HTML ("* User Name can not be null.");
  Else if ($ ("#userPassword"). val () = "" "
  	$ (" #error_message "). HTML (" * Password can not be null. "); 			
  else {
  	$.post (
  	        "Checklogin.action",
  		{"username": $ ("#username"). Val (), "Password": $ ("#password"). Val ( )},
  		function (data) {
  		        if (data.suc) {
  			        location.href= "userlist.action";
  		        } else {
  				$ ("#error_ Message "). HTML (" * The username or password is incorrect. ");			
  			}
  		,
  		" json ");
 }	

The above two methods, in HTML, form forms are not allowed to appear

<form method= ""  action= ""////>
    ///////
</form>

Otherwise there is an error (click no response, JS function inside the JSON way POST method is not performed).

Remove,<form></form>