Open Closed Principle

Bird.js

// Bad
class Bird{}
class FlyingBird extends Bird {
  constructor(type, name){
    super();
    this.name = name
  } 
  flightSpeed(){
    if(this.name === "parrot" || this.name === "dove"){
      return ('I can fly medium-fast')
    }
    else if(this.name === "eagle") {
      return ('I can fly  fast)
    }
  }
}
              
// Good
              
class BirdTwo{}
class FlyingBird extends BirdTwo{
  constructor(type, name){
    super();
    this.name = name
    } 
  flightSpeed(){
      return 'I can fly'
    }
 }
            
class mediumFlyer extends FlyingBird{
    constructor(type, name){
    super();
    this.name = name
  } 
  flightSpeed(){
      return 'I can fly medium fast'
  }
}