Pythagorean.js

function Pythagorean() {}
Pythagorean.prototype.calculate = function(obj) {
    if (Object.keys(obj).length > 3 ) {
        throw 'This function accepts object with maximum of 3 properties';
    }
    if ( typeof obj.c === 'object' ) {
        return Math.sqrt(Math.pow(obj.a,2) + Math.pow(obj.b,2));
    }
    else {
        if ( obj.c <= obj.a || obj.c <= obj.b ) {
            throw 'Hypotenuse must be larger than any of the other two sides';
        }
        var num = obj.a || obj.b;
        return Math.sqrt(Math.pow(obj.c,2) - Math.pow(num,2));
    }
}
var sides = { a : 3, b : null, c : 13 }
console.log(new Pythagorean().calculate(sides));