what are ES6 class getter and setter actually?

feiyuerenhai picture feiyuerenhai · Jan 7, 2017 · Viewed 28.7k times · Source

what are actually getter and setter methods in ES6 class definition? are they infact prototype props ? for examle:

class Person{
  constructor(){};
  get name(){
    return 'jack';
  }
  set name(){
    // ???
  }
}

does this equals to Person.prototype.name = 'jack';

and another question, i ve seen examples of setters which utilizes the instance's prop like:

class Person{
  constructor(){
    this._name = 'jack';
  };
  get name(){
    return this._name;
  }
  set name(val){
    this._name = val;
  }
}

i dont wanna do this way, i want something like:

class Person{
  constructor(){};
  get name(){
    return 'jack';
  }
  set name(val){
    // like this
    // name = val;
  }
}

what could be done?

Answer

Tiago Marinho picture Tiago Marinho · Jan 7, 2017

Yes, it can be done: Just drop the setter/getter syntax and add a property to the class during initialization instead:

class Person{
    constructor(name){
        this.name = name;
    }
}

The getter/setter syntax exists for properties that must be calculated based on other properties, like the area property from a circle of a given radius:

class Circle {
    constructor (radius) {
        this.radius = radius;
    }
    get area () {
        return Math.PI * this.radius * this.radius;
    }
    set area (n) {
        this.radius = Math.sqrt(n / Math.PI);
    }
}

Or getting the full name of a Person object with firstName and lastName properties. You get the idea.