How to extend class prototype in TS?

Question

typescript

Need something like this (error - foo not found):

interface String {
   foo(): number;
}

String.foo= function() {
   return 0;
}

String.prototype.foo= function() {
   return 0;
}

Answer 1

declare global {
    interface String {
        foo(): number;
    }
}

String.prototype.foo = function () {
    return 0;
};

Description here