Determine the type of a function to assign to the parent object's property

Consider the following scenario:

class SomeClass {
    public someProperty;

    public someMethodA(): void {
         this.someProperty = this.someMethodB()
    }

    public someMethodB() {
        ...some code...
    }
}

I need the type of someProperty to match the type returned by someMethodB. For example, if someMethodB returns a number, then someProperty should also be of type number. If there are any changes made to someMethodB that result in a different return value type, the type of someProperty should automatically adjust accordingly.

Answer №1

An example of referencing a method type using a lookup type can be seen in the code snippet below. By utilizing the SomeClass["someMethodB"] syntax, you can access the type of the method and then extract its return type using the built-in type alias ReturnType:

public myType: ReturnType<SomeClass["someMethodB"]>;

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