How to call a function's methods from within another function

Question

In the form object below, from within the "check" function, how do I call the "show" and "hide" methods of the notification function?

(function (namespace, $, undefined) {
    var form = {
        check : function(){
            form.notification.show(); // Generates an error
        },

        notification : function(){
            this.show = function(){
                ...
            };
            this.hide = function(){
                ...
            };
        }
    };
}(window.namespace = window.namespace || {}, jQuery));

With form.notification.show() I get the following error:

Uncaught TypeError: Cannot read property 'show' of undefined

Aaron Digulla · Accepted Answer · 2014-11-10 10:19:26Z

1

Try to define notification outside form and then refer to it:

var notification : { // no function here
        show : function(){...}, // avoid "this"
        hide : function(){...}
};

var form = {
    check : function(){
        notification.show(); // <-- Use here
    },

    notification : notification // and here
};

(I omitted the jQuery protection code for clarity).

The next problem is that you this.show = will assign the function to whatever this is when the function notification() is executed. this isn't notification!

edited Nov 10, 2014 at 10:19

answered Nov 6, 2014 at 13:17

Aaron Digulla

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6 Comments

verism Over a year ago

Strange - this doesn't appear to have any effect. I'm wondering now if there's a conflict in my "working" code...

verism Over a year ago

Well, it seems that I do have access to the notification function in my original code. If I run console.log(form.notification) from within the check function, it returns the script. Any thoughts?

Aaron Digulla Over a year ago

See my edits. show is put into this and this !== form.notification (most likely).

verism Over a year ago

You're right - this referred to the form object. Making notification an object seems to be the obvious fix.

Aaron Digulla Over a year ago

I've improved my answer again. If it solves your problem now, please accept it.

|

Jay · Accepted Answer · 2014-11-06 13:21:34Z

0

You've enclosed it, so you need to return it and that will expose it for you, if you whip the following in chrome console, you'll see you have access to the form object

(function (namespace, $, undefined) {

var form = {

        check : function(){
            form.notification.show(); // Generates an error
        },

        notification : function(){
            this.show = function(){

            };
            this.hide = function(){

            };
        }


};
return{form:form};}(window.namespace = window.namespace || {}, jQuery));

All i've done to your code is added

return{form:form};

After the form object. Hope this helps

EDIT

If you want to only expose certain parts of the form, for example only notifications, you could modify the return like so:

return{form.notification: notification}

edited Nov 6, 2014 at 13:21

answered Nov 6, 2014 at 13:13

Jay

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3 Comments

verism Over a year ago

Not entirely sure why it was downvoted either. However, this isn't a viable option as nothing may follow the return statement.

Jay Over a year ago

Not true copy the above code and paste it into your console. then type in window.namespace and see what it returns.

Alnitak Over a year ago

I downvoted it because at that point the answer was just a block of code with no explanation. Also, it's almost always a bad idea to reference an object by its external name from within that object - in most cases it should be accessible as this.

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