Explanation of ecmascript 6 (ES2015) classes, class inheritance, super calls and static methods. Compiled online on babel site: https://goo.gl/vfdkpC

es6_classes.js

class BaseClass {
	constructor(name, age) {
		this.name = name;
		this.age = age;
	}
	static getDescription() {
		return "this function can be called without instantiating BaseClass";
	}
	getData() {
		return ["base data is:", this.name, this.age].join(' ');
	}
}

let base = new BaseClass('Al Pacino', 75);
console.log(base); // logs {"name":"Al Pacino","age":75}
console.log(base.getData()); // logs "base data is: Al Pacino 75"
console.log(BaseClass.getDescription()); // *** not "base.getDescription()"

class Person extends BaseClass {
	constructor(name, gender, age) {
		super(name, age);
		this.gender = gender;
	}
	speak() {
		return `Hi, I'm ${this.name}. I'm ${this.age} years old and i am ${this.gender}.`;
	}
	getData() {
		return ["person data is:", this.name, this.gender].join(' ');
	}
	getInfo() {
		return super.getData(); // *** not "this.getData()" 
	}
}

let person = new Person('johny', 'male', 27);

console.log(person); // logs {"name":"johny","age":27,"gender":"male"}
console.log(person.speak()); // logs "Hi, I'm johny. I'm 27 years old and i am male."
console.log(person.getData()); // logs "person data is: johny male"
console.log(person.getInfo()); // logs "base data is: johny 27"

Shouldn't console.log(person.getInfo()); log data is: johny 27, instead of base data is: johny 27?

That's correct, updated the code (line 10). Thanks!