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Abstract Class

An abstract classabstract class abstract class , sometimes also called a templatetemplate template , is a class from which an object cannot be instantiated directly.

As of July 2017, there is no native support for abstract classes and interfaces. However, you can do the following:


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

class Food{
   constructor(b){
      if (new.target === Food)                                        // or:
  this.contructor === Food
         throw new TypeError("Cannot instantiate from an Abstract Class directly! Food");
      if (this.brand === undefined)
          throw new TypeError("brand() must be defined -- Food");
   }}class DogFood extends Food{}//var h = new Food;            // TypeError: Cannot instantiate from an Abstract Class directly! -- Foodvar o = new DogFood;         // TypeError: brand() must be defined – Food

</script></body><html>

Every time a 'new' keyword is used to instantiate an object (eg. new Food), the class (ie. Food)is assigned to a meta property, new.targetnew.target new.target , which can be accessed within the constructor.