typescript - Validate interface of function call

Question

I have a the following code:

myArray: { value: string; name: string; }[]; 

orderFunction (a, b) {
    if (a.wrong > b.wrong) {
        return 1;
    } else {
        return -1;
    }
}

myArray.sort(orderFuncion);

The above code should give an error as the elements in the array don't have the wrong property, but it does not

The definition of sort is correct:

/**
  * Sorts an array.
  * @param compareFn The name of the function used to determine the order of the elements. If omitted, the elements are sorted in ascending, ASCII character order.
  */
sort(compareFn?: (a: T, b: T) => number): this;

but orderFunction is typed as (any any)

How can I make typescript validate it automatically ?

question from:https://stackoverflow.com/questions/65916641/validate-interface-of-function-call

Answer 1

the paramaters a and b are both typed any because you haven't annotated them with a type.

orderFunction (a: { value: string; name: string; }, b: { value: string; name: string; }) {
    if (a.wrong > b.wrong) {
        return 1;
    } else {
        return -1;
    }
}

or in a generic way

orderFunction<T> (a: T, b: T) {
    if (a.wrong > b.wrong) {
        return 1;
    } else {
        return -1;
    }
}

will give you the desired error because the type { value: string; name: string; } does not have a wrong property.

If you don't want implicit any to be a thing you can set noImplicitAny: true in your tsconfig.json.