add mousewheel eventlistener error

Question

Here is the problem :

i have a function, which should return nothing... it is called :

function zoom(event){
    alert("wheel delta : "+event.wheelDelta);
    return false;
}

on click on my element, i try to add an event listener on mousewheel this way :

element.addEventListener("mousewheel",zoom,false);

element is a svg tag. but, function zoom is never called, i only get this message back :

TypeError: Argument 2 of EventTarget.addEventListener is not an object.

what am I doing wrong?

Thanks for help :)

EDIT : here is the whole code :

function ZoomMain(){
var zoom = 0;
var main;
var clicks = 0;
this.click = function(event,svg){
    if(svg){
        switch(clicks%2){
            case 0 :
                main = svg;
                main.addEventListener("mousewheel",zoom,false);
                clicks++;
            break;
            case 1 :
                main.removeEventListener("mousewheel",zoom,false);
                clicks++;
            break;
        }
    }else{
        alert("ERROR");
    }
};

function zoom(event){
    alert("wheel delta : "+event.wheelDelta);
    return false;
}
}

Answer 1

try

if(typeof zoom === "function"){
    element.addEventListener("mousewheel",zoom,false);
}
else{
    alert(zoom);
}

if zoom is not a function probably that's a scope issue. Add all relevant code for more help.

PS: This is not a solution to the problem, but a solution to debug! If you are ok with developer tools, dubyg using that to see if zoom has a valid value.

on click on my element, i try to add an event listener on mousewheel

Paste the click event handler and how you are binding mousewheel event handler inside click event handler. Also show where zoom is defined with relative to these.

http://jsfiddle.net/vucfrfke/3/

stupid issue, you redeclared zoom