Typescript interface default values

Question

I have the following interface in TypeScript:

interface IX {
    a: string,
    b: any,
    c: AnotherType
}

I declare a variable of that t

Answer 1

Factory method:

You could use a factory method for this which returns an object which implements the XI interface.

Example:

class AnotherType {}

interface IX {
    a: string,
    b: any,
    c: AnotherType | null
}

function makeIX (): IX {
    return {
    a: 'abc',
    b: null,
    c: null
    }
}

const x = makeIX();

x.a = 'xyz';
x.b = 123;
x.c = new AnotherType();

The only thing I changed with regard to your example is made the property c both AnotherType | null. Which will be necessary to not have any compiler errors (This error was also present in your example were you initialized null to property c).