Introduction to JavaScript Object Property Descriptors

1 year ago
Jackson Davis
1 minute

The property descriptor in JavaScript is an object used to describe the characteristics of an object property. Each object property has a set of attributes, such as: writability, enumerability, configurability, and value.

There are two types of property descriptors: data descriptors and accessor descriptors.

  1. Data descriptor:
  2. Value: the value of an attribute.
  3. Is the value of the writable property writable (true/false)?
  4. Is the enumerable property of the object true or false, i.e. can it be traversed through a for…in loop?
  5. Configurable: Specifies whether the property can be modified or deleted (true/false).
  6. Accessor descriptors:
  7. Getter function of the attribute ‘get’, called when retrieving the attribute value.
  8. setter function of the property, called when setting the property value.
  9. enumerable: whether the property is enumerable.
  10. configurable: whether the property can be modified.

You can use the method Object.getOwnPropertyDescriptor(obj, prop) to obtain the property descriptor. For example:

const obj = {
  name: 'John',
  age: 25
};

const descriptor = Object.getOwnPropertyDescriptor(obj, 'name');
console.log(descriptor);

The output is:

{
  value: 'John',
  writable: true,
  enumerable: true,
  configurable: true
}

This example demonstrates how to get the property descriptor of an object. It can be seen that the ‘name’ property is writable, enumerable, and configurable.

bannerAds