The has() method of WeakSet instances returns a boolean indicating whether an
object exists in this WeakSet or not.
Syntax
has(value)
Parameters
value- : The value to test for presence in the
WeakSet.
- : The value to test for presence in the
Return value
Returns true if an element with the specified value exists in the WeakSet object; otherwise false. Always returns false if value is not an object or a non-registered symbol.
Examples
Using the has() method
const ws = new WeakSet();
const obj = {};
ws.add(window);
ws.has(window); // returns true
ws.has(obj); // returns false
// Storing a non-registered symbol
const sym = Symbol("foo");
ws.add(sym);
ws.add(Symbol.iterator);