Determine if a JavaScript property has a getter or setter defined?

Question

Is it possible, given an object and property name to determine if that property is defined using either a getter or setter, or is it completely transparent? I only want to define a getter/setter if there is not already one defined on the property.

I need it to work in WebKit/Firefox.

Answer 1

I think you're looking for getOwnPropertyDescriptor?

Answer 2

You can use Object.getOwnPropertyDescriptor(obj, prop)

For example:

var obj = { first: 1 } obj.__defineGetter__('second', function() { return 2; });  // get descriptors var descriptor1 = Object.getOwnPropertyDescriptor(obj, 'first'); var descriptor2 = Object.getOwnPropertyDescriptor(obj, 'second');  // check if it's a getter  descriptor2.get // returns function () { return 2; }  descriptor1.get // returns undefined