Reference

Objects are never copied. They are passed around by reference.

  1.  // Imagine I had a pizza
  2. var myPizza = {slices: 5};
  3.  // And I shared it with You
  4. var yourPizza = myPizza;
  5.  // I eat another slice
  6. myPizza.slices = myPizza.slices - 1;
  7. var numberOfSlicesLeft = yourPizza.slices;
  8.  // Now We have 4 slices because myPizza and yourPizza
  9.  // reference to the same pizza object.
  10. var a = {}, b = {}, c = {};
  11.  // a, b, and c each refer to a
  12.  // different empty object
  13. a = b = c = {};
  14.  // a, b, and c all refer to
  15.  // the same empty object