ES6 methods implementation

es6-methods.js

class Foo {
  test() {
    return 'Foo';
  }
}
 
class Bar extends Foo {
  test() {
    return `${super.test()}Bar`;
  }
}
 
class FooX {
  test() {
    return 'FooX';
  }
}
 
class BarX extends FooX {
  test() {
    return `${super.test()}Bar`;
  }
}
 
const bar = new Bar();
 
// The same signature but different behavior
console.log(Bar.prototype.test.toString() === BarX.prototype.test.toString()); // true
console.log(Bar.prototype.test.call(bar)); // "FooBar"
console.log(BarX.prototype.test.call(bar)); // "FooXBar"