Sometimes, we want to add field initializers with TypeScript.

In this article, we’ll look at how to add field initializers with TypeScript.

How to add field initializers with TypeScript?

To add field initializers with TypeScript, we can use the Partial type.

For instance, we write

class Person {
  public name: string = "default";
  public address: string = "default";
  public age: number = 0;

  public constructor(init?: Partial<Person>) {
    Object.assign(this, init);
  }
}

const p = new Person({ name: "John" });

to set the init parameter of the Person constructor to Partial<Person> so that it takes an object with any property of the Person class.

We add ? after init to make it optional.

Then we merge the properties of init into this with

Object.assign(this, init);

Next, we create a Person instance with

const p = new Person({ name: "John" });

Conclusion

To add field initializers with TypeScript, we can use the Partial type.