typesafe javascript

interface IPerson {
    firstName: string;
    lastName:string;
}
 /**
 * @param Person person
*/
function printPerson(Person:IPerson) {
    
    return 'Hi ,'+ Person.firstName + ' ' + Person.lastName
}


var person = {firstName:'Peter', lastName:'Boethig'}

document.body.innerHTML = printPerson(person);