+ " is not an integer"); // exception throwing        return x;    }    //semicolons are optional (but beware since this may cause consecutive lines to be    //erroneously treated as a single statement)    this.a = checkInt(x)    this.b = checkInt(y)}// The prototype of object instances created by a constructor is // that constructor's "prototype" property.LCMCalculator.prototype = { // object literal    gcd : function() { // method that calculates the greatest common divisor        // Euclidean algorithm:        var a = Math.abs(this.a), b = Math.abs(this.b), t;        if (a < b) {            t = b; b = a; a = t; // swap variables        }        while (b !== 0) {            t = b;            b = a % b;            a = t;        }        // Only need to calculate gcd once, so "redefine" this method.        // (Actually not redefinition - it's defined on the instance itself,        // so that this.gcd refers to this "redefinition" instead of LCMCalculator.prototy