Deep jQuery.extend modifies the target's protype?

Deep jQuery.extend modifies the target's protype?

After running the following code, parent.deep.y returns "baz" even though parent is the prototype of the target.

  1. var parent = {
  2.   deep: { x: "foo", y: "bar"}
  3. }
  4. var target = Object.create(parent);
  5. var source = {
  6.   deep: { y: "baz" }
  7. };

  9. $.extend(true, target, source);

I expected parent.deep.y to retain it value of "bar".

Can someone please explain why is it that a deep $.extend modifies the protoype of the target?