CodeTip - Javascript: Compare class instances

Many times we are in situations we want to compare instances of a class, aka objects, for example in case you develop a game and you want to compare instances of a gameobject, e.g. Car:

class Car { constructor(speed){ this.speed = speed } } 

Let's say we want to compare instances of a car (or sort/filter an array of them). Obviously we can do:

const car1 = new Car(100) const car2 = new Car(120) const car3 = new Car(90) console.log(car2.speed > car1.speed) // true const sorted = [car1, car2, car3].sort((a,b) => { return a.speed - b.speed; }); 

This works perfectly fine but we can do better, so we don’t have to type .speed every time we want to compare two cars, or sort/filter an array of them. We can define a valueOf method in the Car class, the method returns the “value” of the instance.

class Car { constructor(speed){ this.speed = speed } valueOf(){ return this.speed; } } const car1 = new Car(100) const car2 = new Car(120) const car3 = new Car(90) console.log(car2 > car1) // true