JavaScript reference

get / set

Properties backed by functions: reading calls get, writing calls set.

Available since: ES5

Syntax

get name() { … } / set name(value) { … }

Examples

A computed property:

class User {
  constructor(first, last) {
    this.first = first;
    this.last = last;
  }
 
  get fullName() {
    return `${this.first} ${this.last}`;
  }
}
 
console.log(new User('Anna', 'Smith').fullName);

Output:

Anna Smith

Validating a value on write:

class Product {
  #price = 0;
 
  get price() {
    return this.#price;
  }
 
  set price(value) {
    if (value < 0) throw new RangeError('Price cannot be negative');
    this.#price = value;
  }
}
 
const tea = new Product();
tea.price = 5;
console.log(tea.price);
 
try {
  tea.price = -1;
} catch (error) {
  console.log(error.message);
}

Output:

5
Price cannot be negative

Notes

A getter is read like a property, without parentheses: user.fullName, not user.fullName(). A getter without a setter makes the property read-only. It works in plain objects too: { get total() { … } }.

In the tutorial

Getters and setters — Getters and setters in JavaScript classes: computed properties, validating values on write and read-only properties.

Thanks for reading!