When working with objects of type IBob, it is important to ensure that all fields required by IBob are defined. One way to achieve this is by creating the object as a fully formed IBob instance:
let bob: IBob = Object.assign({
anotherValue: 2,
aFunction : (): number => {
return 3;
}
}, alice);
If you only want to partially initialize the object and have some fields missing, you can use Partial:
let bob: Partial<IBob> = Object.assign({}, alice);
bob.anotherValue = 2;
bob.aFunction = (): number => {
return 3;
}
While making all fields optional using Partial may not always be suitable, it is a good option to consider. You can also make just the fields of IBob optional while keeping the ones from IAlice mandatory for more advanced typing:
let bob: Partial<Pick<IBob, Exclude<keyof IBob, keyof IAlice>>> & IAlice = Object.assign({}, alice);
bob.anotherValue = 2;
bob.aFunction = (): number => {
return 3;
}
It is crucial to be specific about optional fields, especially under strictNullChecks, as you will need to explicitly check for null before accessing optional fields. If you choose to proceed with a type assertion, be cautious as it can lead to errors if not done accurately:
let bob: IBob = Object.assign({}, alice) as IBob;
// Or (but only if you are not in a tsx file)
let bob: IBob = <IBob>Object.assign({}, alice);