Question

In Javascript to find all the values in a hash I have seen the following code:

var myHash = {};
myHash['one'] = 1;
myHash['two'] = 2;
for (var key in myHash) {
    if (myHash.hasOwnProperty(key)) {
        //do something
    }
}

What is the point of having the hasOwnProperty check here?

Answer 1

The point is to make sure that key is a property defined directly on myHash and not one that was inherited through a prototype chain. Using in doesn’t automatically filter out inherited properties, so you get to do it yourself.

But, as others have said, it isn’t necessary for your particular example.

Source: hasOwnProperty on MDN.