Has method in TypeScript

In TypeScript, you can check if a class has a method using the typeof operator. The typeof operator gives the type of the operand. If the operand is a class name, then the type is the constructor function, and you can check for the method using the instanceof operator.

Here's an example:

class Person {
  name: string;
  
  constructor(name: string) {
    this.name = name;
  }
  
  sayHello() {
    console.log(Hello, my name is ${this.name});
  }
}
const john = new Person("John");
console.log(typeof Person); // outputs "function"

console.log(john instanceof Person); // outputs "true"

console.log('sayHello' in john); // outputs "true"

In this example, we define a Person class with a sayHello method. We then create an instance of the class and use the typeof operator to get the type of the Person class, which is a constructor function. We also use the instanceof operator to check if the john variable is an instance of the Person class. Finally, we use the in operator to check if the john object has a sayHello method.