How to type new functions?

Question

typescript

Link to the sandbox

interface IPerson {
    name: string;
    sayHello(): string;
}

const Welcome = function (this: IPerson, name: string) {
  this.name = name;
}  

Welcome.prototype.sayHello = function () {
  return "Hello, " + this.name + "!";
};

interface PersonConstructor {
    new(name: string): IPerson;
}

var welcome = new Welcome("John");
console.log(welcome.sayHello());

Throws an error 'new' expression, whose target lacks a construct signature, implicitly has an 'any' type.(7009)

Answer 1

const Welcome = function(this: IPerson,name: string) {
    this.name=name;
} as unknown as PersonConstructor