Object copied to second property via reference persists even after original property deleted?

Question

I thought objects are passed as reference. But when I delete b, it still exists in c. Please see this example:

This first part makes sense

Answer 1

That's because:

The delete operator removes a property from an object. MDN Delete

The entry b that corresponds to the Object {val: true} is removed from a. The entry c in a still refers to this object. If you try deleting c.val or a.b.val, you can still see the effect cascading to the other.

What you're trying to do, i.e, deallocating data and expecting it to be cascaded across, doesn't happen in javascript. If you have a C++ background, consider thinking of all javascript objects as being reference counted. Ican remove a reference to it (i.e, the entry that 'points' to this object), but I can't remove the object itself. That is the pure prerogative of the javascript engine.