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TypeError: getting private setter-only property

The JavaScript exception "getting private setter-only property" occurs when reading the value of a private property for which only a setter is defined.

Message​

TypeError: '#x' was defined without a getter (V8-based)
TypeError: getting private setter-only property (Firefox)
TypeError: Trying to access an undefined private getter (Safari)

Error type​

What went wrong?​

There is an attempt to get the value of a private property for which only a setter is specified. Unlike normal objects, where an undefined getter just means the property would always return undefined, for private properties, this is an error.

Examples​

Private property with no getter​

Here, #name has no getter, so trying to read it using this.#name will throw an error.

class Person {
  set #name(value) {}

  get name() {
    return this.#name;
  }
}

const person = new Person();
console.log(person.name);

It's not usual for a private property to have a setter without a getter. Either add a getter or refactor your program so the setter can be removed too.

See also​