Understanding Static Properties in JavaScript

Previously, we mentioned that functions are also objects, and you may set custom properties for them. Also remember that classes are just constructor functions, so technically, you can assign custom properties for classes as well.

1class User {
2  constructor(name) {
3    this.name = name;
4  }
5}
6
7User.count = 5;
8
9console.log(User.count);

15

Static properties

This is what a static property is. It is a property assigned directly to the class, not to the object it will create when executed with the keyword new.

JavaScript offers another way of creating static properties, using the keyword static.

1class User {
2  constructor(name) {
3    this.name = name;
4  }
5
6  static count = 5;
7}
8
9console.log(User.count);

15

This property does not exist in the object instance that User will create when executed with new.

1let user = new User("John Doe");
2
3console.log(user);
4console.log(user.count); // -> undefined