Fields: modelling objects

Field declarations create properties on a class, allowing Jigs to contain data. A field declaration consists of a name and a type annotation. Optionally, a field declaration can include an initializer to set the property's default value.

export class Potion extends Jig {
  label: string = 'My Potion';
}

If a field doesn't have an initializer, you need to initialize the property value inside the constructor.

export class Potion extends Jig {
  label: string;

  constructor(label: string) {
    super()
    this.label = label
  }
}

Note that you must also add type annotations to the arguments in the method signature. Additionally, remember to call super() before accessing this in the constructor. Forgetting to do so is a common mistake, but your IDE should warn you about it.

Your turn

Let's start with some simple changes to potion.ts:

1. Add a field called label to the class with the type string.
2. Implement a constructor method that takes label as an argument and assigns it to the label property.

Once you're done, you can proceed to the next lesson.