javascript - How to make TypeScript complain about string concatenation with other type?

Question

Why even in strict mode TypeScript is not complaining about this

function test(firstName: string, lastName?: string): string {
    return firstName + " " + lastName;
}

test('John');

Answer 1

As MartinJohns said on a github issue regarding this topic

I think this would belong more to the realm of linters. This is not really a type error, it's just undesired behavior.

no-base-to-string

restrict-plus-operands

restrict-template-expressions

no-implicit-coercion