JavaScript Symbols Using Symbol.for() to create global, shared symbols
Example
The Symbol.for method allows you to register and look up global symbols by name. The first time it is called with a given key, it creates a new symbol and adds it to the registry.
let a = Symbol.for('A');
The next time you call Symbol.for('A'), the same symbol will be returned instead of a new one (in contrast to Symbol('A') which would create a new, unique symbol that happens to have the same description).
a === Symbol.for('A') // true
but
a === Symbol('A') // false
