Undefined error - JS inheritance

function Class(object) {
    this.title = object.title;
    this.getTitle = function() {
        return this.title;
        };
};

var c1 = new Class({
    title: 'This is class'
});



c1.getTitle();
// define here subclass

function SubClass(object) {
    this.title = object.title;
};
SubClass.prototype = new Class();
SubClass.prototype.constructor = SubClass;


// TypeError: Cannot read property 'title' of undefined