动作脚本3：将String变量作为函数调用

Question

I have a function,

function tempFeedBack():void
    {
        trace("called");
    }

and event listener works perfect when I write function name directly like this,

thumbClip.addEventListener(MouseEvent.CLICK, tempFeedBack);

But, when I give the function name as string like this,

thumbClip.addEventListener(MouseEvent.CLICK, this["tempFeedBack"]());

It is not working! It says, TypeError: Error #1006: value is not a function.

Any ideas?

Answer 1

You got that error because simply this["tempFeedBack"]() is not a Function object, which is the listener parameter of the addEventListener() function, in addition, it's nothing because your tempFeedBack() function cannot return any value.

To more understand that, what you have wrote is equivalent to :

thumbClip.addEventListener(MouseEvent.CLICK, tempFeedBack());

Here you can see that you have passed the returned value of your tempFeedBack() function as the listener parameter which should be a Function object, but your tempFeedBack() can return nothing !

So, just to explain more, if you want that what you have wrote work, you should do something like this :

function tempFeedBack():Function 
{
    return function():void { 
            trace("called");
        }
}

But I think that what you meant is :

// dont forget to set a MouseEvent param here
function tempFeedBack(e:MouseEvent):void 
{
    trace("called");
}
stage.addEventListener(MouseEvent.CLICK, this["tempFeedBack"]);
// you can also write it 
stage.addEventListener(MouseEvent.CLICK, this.tempFeedBack);

Hope that can help.