What does explicitly & implicitly mean in JavaScript?

Question

I often see the terms explicitly & implicitly used in JavaScript and I'm still not sure I know what they mean i.e the following text from the MDC site describing the object model.

The constructor function explicitly sets the value of the projects property, and implicitly sets the value of the internal __proto__ property to the value of WorkerBee.prototype...

[source]

Answer 1

"Implicitly" means that the JS engine does it. "Explicitly" means that you must do it.