프로토타입 객체 메서드와 this 바인딩

prototype-chaining8.js

function Animal(species) {
  this.species = species;
}

var frog = new Animal('frog');
frog.getSpecies();//Error

Animal.prototype.getSpecies = function() {
  console.log(this.species);
};
frog.getSpecies();//frog 출력
Animal.prototype.getSpecies();//undefined 출력

Animal.prototype.species = 'animal';
Animal.prototype.getSpecies();//animal 출력