It's the main mechanism in JS to define functional accessors, at least since ECMA-Script 3. Before this, the terms have been used loosely, as well, for explicit

It's the main mechanism in JS to define functional accessors, at least since ECMA-Script 3. Before this, the terms have been used loosely, as well, for explicit accessor methods (like in Java). [Edit] Correction: should have been, at least since ECMA-262 5th Ed.