What are private fields in JavaScript?

What are private fields in JavaScript?

Private fields are a way to create properties in a class that cannot be accessed from outside the class. They are defined using a hash symbol (#) before the field name.

Can you give me an example of how to use private fields?

Sure! Here's a simple example:

class MyClass {
  #privateField;

  constructor(value) {
    this.#privateField = value;
  }

  getPrivateField() {
    return this.#privateField;
  }
}

const myInstance = new MyClass(42);
console.log(myInstance.getPrivateField()); // 42
// console.log(myInstance.#privateField); // This will throw an error!

What happens if I try to access a private field directly?

If you try to access a private field directly from outside the class, it will result in a syntax error. Private fields are strictly encapsulated.

Are private fields supported in all JavaScript environments?

Private fields are part of the ECMAScript 2022 specification, so they are supported in modern browsers and Node.js versions. However, older environments may not support them.