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Prototype VS Static, Getter, Setter


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<!DOCTYPE html><html><body><script>

class Animal {
   constructor(n,a){
      this.name = n; // prototype variable
      this.age = a;  // prototype variable
   }
   eat(){ // prototype method
      console.log(this.name+' is eating.');
   }
   static comment(){  // static method
      console.log('All animals are cute.');
   }
   whoami(){      //this.constructor.eat();  // TypeError
      this.constructor.comment();                           // this.constructor.staticFunction() allowed
      console.log('I am a nice '+this.constructor.name+'.');
   }
   get intro(){  // getter, to act like prototype variable
      return 'This is '+this.name+'.';
   }
   set rename(n){ // setter
      this.name = n;
   }}Animal.prototype.sex = 'm';                                                                   // prototype variableAnimal.prototype.drink = function(){console.log(this.name+' is drinking.');}  // prototype methodAnimal.message = 'We should protect all animals.';                                      // static variableAnimal.comment2 = ()=>console.log(Animal.message);                              // static methodvar b = new Animal('Brownie',5);console.log(b.age,b.sex); // 5 "m"b.eat();                           // Brownie is eating.b.drink();                        // Brownie is drinking.b.whoami();                    // All animals are cute. I am a nice Animal.Animal.comment();          // All animals are cute.Animal.comment2();        // We should protect all animals.console.log(b.intro);         // This is Brownie.b.rename='Greenie';b.drink();                        // Greenie is drinking.console.log(typeof b);      // object console.log(b instanceof Animal); // true//let m1=b.eat; m1();        // TypeError ('this' is undefined)let m2=Animal.comment; m2(); // All animals are cute.

</script></body><html>

Note how you verify the class name of an object with instanceofinstanceof instanceof .

A class declaration is not hoisted, ie. a class cannot be used before its declaration. Also, a class cannot be redeclared.