WeakSet.prototype.has()
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.
The has() method of WeakSet instances returns a boolean indicating whether an
object exists in this WeakSet or not.
Try it
Syntax
js
has(value)
Parameters
value-
The value to test for presence in the
WeakSet.
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
js
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);
Specifications
| Specification |
|---|
| ECMAScript Language Specification # sec-weakset.prototype.has |
Browser compatibility
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