calling removeEventListener from within event listener?

Question

I have some simple code, but currently it does not remove the listener after the first call. How can I achieve this? Or do I really need to add redundant if/else checks on a var set upon notice?

    document.addEventListener("contextmenu", function(e){
        alert("Please remember this is someone's art! Give credit where it is deserved!");
        document.removeEventListener("contextmenu", function(e){
            console.log('User has been warned...');
        });
    }, false);

Updated code Still same message every right click

    document.addEventListener("contextmenu", function msg(e){
        alert("Please remember this is someone's art! Give credit where it is deserved!");
        e.removeEventListener("contextmenu", msg, false);
    }, false);

Answer 1

you need to pass the same function to remove as add.

the easy way to do that is to give the function a name and pass the name to removeEventListener():

 document.addEventListener("contextmenu", function me(e){
        alert("Please remember this is someone's art! Give credit where it is deserved!");
        document.removeEventListener("contextmenu", me, false);
    }, false);

see https://developer.mozilla.org/en-US/docs/Web/API/EventTarget.removeEventListener for a good overview

obligatory fiddle: http://jsfiddle.net/w1kzLkoL/

tested in chrome, firefox, and IE10

Answer 2

You may try this example:

 document.addEventListener("contextmenu", (function() { var done = false; return function(e) { if (!done) { done = true; alert('Warning !'); } console.log('done ...', done); e.preventDefault(); return false; }; })(), false); 

 Open console... right click