1. javascript built-in: map: `map()` constructor

2. javascript built-in: map: `map()` constructor: `new map(iterable)`

3. javascript built-in: map: `map()` constructor: `new map(null)`

4. javascript built-in: weakmap: `weakmap()` constructor

5. javascript built-in: weakmap: `weakmap()` constructor: `new weakmap(iterable)`

6. javascript built-in: weakmap: `weakmap()` constructor: `new weakmap(null)`