Detecting an undefined object property

Question

What\'s the best way of checking if an object property in JavaScript is undefined?

Answer 1

I didn't see (hope I didn't miss it) anyone checking the object before the property. So, this is the shortest and most effective (though not necessarily the most clear):

if (obj && obj.prop) {
  // Do something;
}

If the obj or obj.prop is undefined, null, or "falsy", the if statement will not execute the code block. This is usually the desired behavior in most code block statements (in JavaScript).