Understanding Javascript Form Onsubmit

Question

Trying to cancel the sending of an empty form. Confused as there seems to be no reason why this doesnt work. Using firefox as my browser.

Could anybody explain why this code does not cancel the form being sent yet it fires the alert dialog.

addEvent(searchForm, "onsubmit", function(){
 if(inputBox.value.trim() === ""){
 alert("empty"); //this line gets called
 return false; //this doesn't 
 }
});

Many Thanks

this is the addEvent function

function addEvent(element, listener, func){ 
 if(element.addEventListener){
 listener = listener.substr(2, listener.length);
 element.addEventListener(listener, func);
 } else {
 element.attachListener(listener, func);
}
}

• Fabrício Matté: Now it is answerable. =]

Answer 1

your handler should be

function(e){
 if(inputBox.value.trim() == ""){
 alert('empty');
 e.preventDefault();
 }
}

Normally regardless of the framework used handlers support passing the event itself as an argument.

Answer 2

addEvent is not a native javascript function.

use this instead..

 searchForm.onsubmit = function(e){
 if(inputBox.value.trim() === ""){
 alert("empty");
 e.preventDefault();
 return false;
 }
 }