intercept form submit with jQuery

Question

I want to intercept a submit via jQuery and first check if a file is present on the server. If it's present continue with the request, if not display a message and don't send the request. This is what I have:

$("#methodForm").submit(function(e){      checkIndex('upload/segments.gen').done(function() {         return true;     }).fail(function () {         e.preventDefault();         alert("No index present!");         return false;     }); }); 

this is the checkIndex():

function checkIndex(file){     return $.ajax({         url : file,         type:'HEAD'     }); } 

What happens is this: The file is present on the server, but the checkIndex returns with fail. First I see the alert popup and then it continues and sends the post request to the server.

I use the checkIndex() for other purposes as well where it works like expected so I'm pretty sure the error is somewhere in the submit routine. But I can't find out what's wrong with it.

Answer 1

You can't return out of a callback to an asynchronous method(such as ajax). Instead, prevent the submit all together, then submit it when you are ready.

$("#methodForm").submit(function(e){     e.preventDefault();     var form = this;     checkIndex('upload/segments.gen').done(function() {         form.submit(); // submit bypassing the jQuery bound event     }).fail(function () {         alert("No index present!");     }); });