"By reference" means different things to different people.
The most accurate statement I've found is that JavaScript, much like Java, passes reference-by-value. Everything is passed by value, but if your value is an object, then the new scope gets a copy of the reference. If you modify the object by dereferencing (that is, `a.foo = "bar";`), your modifications to the object persist outside of your scope.
This is an important understanding to have when working with JavaScript.
The most accurate statement I've found is that JavaScript, much like Java, passes reference-by-value. Everything is passed by value, but if your value is an object, then the new scope gets a copy of the reference. If you modify the object by dereferencing (that is, `a.foo = "bar";`), your modifications to the object persist outside of your scope.
This is an important understanding to have when working with JavaScript.