What's the fastest way to iterate over an object's properties in Javascript?

Question

I know that I can iterate over an object\'s properties like this:

for (property in object)
{
    // do stuff
}

I also know that the fastest

Answer 1

The for/in loop is the best way to enumerate properties of a Javascript object. It should be understood that this will only loop through "enumerable" properties, and in no particular order. Not all properties are enumerable. All properties/methods added programmatically via your own Javascript code will be enumerable, but predefined properties/methods that are inherited (such as toString) are not usually enumerable.

You can check enumerability like so...

var o = new Object();
alert(o.propertyIsEnumerable("toString"));