Question

I want to know which of these methods is better:

var Obj = Obj || {};

or

if (Obj === undefined || typeof Obj !== 'object') {
  Obj = {};
}

I’ve been told that the 2nd method is better, but I don’t know why. Please can you explain to me what are pros and cons of each.

Many thanks

Answer 1

The second method is simply more specific, so for the purpose of creating an object (if it does not already exist), it is better. The first method only tests if the object is “truthy”, meaning if Obj was the number 5, it would still return the original Obj, whereas in the second method, Obj must be of type ‘object’ in order for its value to be preserved.

Practically speaking, there isn’t much of a difference, because you rarely run into situations like above; the second method just tells the reader what you want, more specifically. I like the first method because it’s shorter, but it depends on how specific you want to be.