jquery - JSP form still submitting even though JavaScript validation returning false -

i have jsp form "deletecont" , javascript file function "validatedelete". when click "delete contact" button "validatedelete" function called , alert "alertmessage" displayed. however, "contactmaint" servlet still called though false being returned. please can tell me going wrong?

<form name="deletecont"     onsubmit="return validatedelete('${sessionscope.account}','${sessionscope.firstname}', '${sessionscope.lastname}')"      action="contactmaint" method="post">     <input type="submit" value="delete contact" name="delcontact"> </form>       function validatedelete(account, contactfirstname, contactlastname) {     urlstrg = "http://localhost:8080/salespoliticalmapping/jcheckcontacts?account=" +         account + "&firstname=" + contactfirstname + "&lastname=" + contactlastname;     $.get(urlstrg, function (result, status) {         if (result.length > 0) {             var alertmessage = "can't delect contact:";             (var = 0; < result.length; i++) {                 alertmessage += result[i];             }             alert(alertmessage);             return false;         }     }); } 

i have amended code follows although i'm not entirely sure why:

function validatedelete(account, contactfirstname, contactlastname) { $.ajaxsetup({async: false}); urlstrg = "http://localhost:8080/salespoliticalmapping/jcheckcontacts?account=" +  account + "&firstname=" + contactfirstname + "&lastname=" + contactlastname;  var valid = true; var alertmessage = "";  $.get(urlstrg, function(result, status) {    if (result.length > 0) {    valid = false;        alertmessage = "can't delect contact:";    (var = 0; < result.length; i++) {        alertmessage += result[i];         }    }  });   if (valid===false) {      alert(alertmessage);  return false;}  }; 

there 2 problems:

1. you're firing ajax request. ajax requests default asynchronous. after $.get() called, code advances next line while asynchronous request runs in background in different thread. there's in case apparently nothing after $.get(), returns (implicitly true).

2. you're returning callback function, not main function. callback function returns main function, not outside. need return main function.

one way return false , explicitly submit form on success.

function validatedelete(...) {     var $form = $(this);      $.get(..., function(...) {          if (success) {             $form.submit();         }     });      return false; } 

another way making ajax request asynchronous passing { async: false } option 2nd argument of $.get().

function validatedelete(...) {     var valid = false;      $.get(..., { async: true }, function(...) {          if (success) {             valid = true;         }     });      return valid; } 

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please note problem has nothing jsp. you'd still have had same problem when using same script in view technology, such php, asp, etc, , in plain html page. jsp in context of question merely html code generator , can better omitted question in future problems html+css+js/jquery.