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

[object Object] is the default string representation of a JavaScript Object. It is what you'll get if you run this code:

alert({}); // [object Object]

You can change the default representation by overriding the toString method like so:

var o = {toString: function(){ return "foo" }};
alert(o); // foo