Removing event listeners with anonymous function calls in JavaScript

Question

I'm trying to remove an event listener for created span elements where the function called is within a closure. I've tried various methods and none seem to work.

var MyClass = function () {}

MyClass.prototype.addSpan = function (el) {
    var span = document.createElement('span');
    span.innerHTML = "Text here";
    el.appendChild(span);
    span.addEventListener('click', (function (obj) { 
        return function () { 
            obj.removeSpan(); 
        }
    })(this), false);
}

MyClass.prototype.removeSpan = function () {
    alert('removing span');
    this.removeEventListener('click', arguments.callee, false);
    // .... remove span .... 
}

myclass = new MyClass();

myclass.addSpan(document.getElementById('box'));

I've also used

this.removeEventListener('click', (function (obj) { 
    return function () { 
        obj.removeSpan(); 
    }
})(this), false);

in place of this.removeEventListener('click', arguments.callee, false); but had no luck.

Any help is much appreciated!

Answer 1

var MyClass = function () {}
MyClass.prototype.listener=null;
MyClass.prototype.addSpan = function (el) {
    var span = document.createElement('span');
    span.innerHTML = "Text here";
    el.appendChild(span);
    span.addEventListener('click', (function (obj) { 
        return obj.listener = function () { 
            obj.removeSpan(this); // here 'this' refers to 'span'
        }
    })(this), false);
}

MyClass.prototype.removeSpan = function (el) {
    alert('removing span');
    el.removeEventListener('click', this.listener, false);
    // .... remove span .... 
}

myclass = new MyClass();
myclass.addSpan(document.getElementById('box'));

Without a reference of the listener you can't remove it, so I've also added a property (listener) to the MyClass' prototype and then returned the reference as return obj.listener and also you need to pass the object as I've passed it obj.removeSpan(this); and in the removeSpan I've received with el so I could've done el.removeEventListener, hope it helps.

You can also do this

var MyClass = function () {this.listener=null;}

instead of

MyClass.prototype.listener=null;

Here is an example.

Answer 2

Try changing your event handler to this.

span.addEventListener('click', (function (obj) { 

        span.onclick = null;

        return function () { 
            obj.removeSpan(); 
        }
    })(this), false);