What is the central concept of JavaScript memory management?

The central concept of JavaScript memory management is a concept of reachability.

1. A distinguished set of objects are assumed to be reachable: these are known as the roots. Typically, these include all the objects referenced from anywhere in the call stack (that is, all local variables and parameters in the functions currently being invoked), and any global variables.

2. Objects are kept in memory while they are accessible from roots through a reference or a chain of references.