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.

After reading all the answers, I am using the following inheritance mechanism:

var SuperClass = function(){    this.info = "I am superclass";    console.log("SuperClass:");};SuperClass.prototype.printInfo = function(){    console.log("printing from superclass printInfo");    console.log("printinfo");    console.log(this.info);};var SubClass = function(){    SuperClass.call(this);};SubClass.prototype = Object.create(SuperClass.prototype);SubClass.prototype.constructor = SubClass;SubClass.prototype.printInfo = function(){    console.log("calling superclass");    Object.getPrototypeOf(SubClass.prototype).printInfo.call(this);    console.log("called superclass");};var sc = new SubClass();sc.printInfo();

You can write it like this :

SuperClass.prototype.printInfo = function(){  console.log("printing from superclass printInfo");  console.log(this.info); };SubClass.prototype.printInfo = function(){  console.log("calling superclass");  SuperClass.prototype.printInfo.call(this);  console.log("called superclass");};