Proper way to call superclass functions from subclass

You are messing with the SubClass‘s prototype with the SuperClass‘s object, in this line

SubClass.prototype = new SuperClass();

the child’s prototype should depend on the Parent’s prototype. So, you can inherit like this

SubClass.prototype = Object.create(SuperClass.prototype);

Also, it is quite normal to change the constructor to the actual function, like this

SubClass.prototype.constructor = SubClass;

To keep your implementation generic, you can use Object.getPrototypeOf, to get the parent prototype in the inheritance chain and then invoke printInfo, like this

SubClass.prototype.printInfo = function() {
    Object.getPrototypeOf(SubClass.prototype).printInfo(this);
};

Since, info is defined in the SubClass yet, it will print undefined. You might also want to call the parent’t constructor, like this

var SubClass = function() {
    SuperClass.call(this);
};

Note: You are creating global variables, by omitting var keyword before SuperClass and SubClass.