OptionalParameter.ts

//optional parameter
function Area(Rad : number , PI  ? : number):number
{
    let Ans : number = 0;
    
    if (PI == undefined){
        PI = 3.14;
    }

    Ans = PI * Rad * Rad;

    return Ans;
}

var Ret : number = 0;

Ret = Area(20.3,3.14);
console.log("Area is : "+ Ret);

Ret = Area(20);
console.log("Area is : "+ Ret);