What does [object Object] mean?

Question

I am trying to alert a returned value from a function and I get this in the alert:

[object Object]  

Here is the JavaScript code:

Answer 1

The default conversion from an object to string is "[object Object]".

As you are dealing with jQuery objects, you might want to do

alert(whichIsVisible()[0].id);

to print the element's ID.

As mentioned in the comments, you should use the tools included in browsers like Firefox or Chrome to introspect objects by doing console.log(whichIsVisible()) instead of alert.

Sidenote: IDs should not start with digits.