javascript object property lookup

Question

Due to object in javascript is associative map (HashMap in other programming languages) does next code

for (var prop in object) {
    if (prop === someConc         


        

Answer 1

I guess for the first one you meant:

if ('prop' in obj) {
  // ...
}

Then you can talk about speed differences and different behavior.

Homework:

var obj = { prop: undefined }; // a bit philosophical...