why do we need static methods in class of javascript

user_10367975 0
Viewed 1855

why do we need static methods in class of javascript.

class Car {
  constructor(brand) {
    this.carname = brand;
  }
  static hello(x) {
    return "Hello " + x.carname;
  }
}

mycar = new Car("Ford");

document.getElementById("demo").innerHTML = Car.hello(mycar);

I know that , Static methods are called directly on the class (Car from the example above) - without creating an instance/object (mycar) of the class. But what's the use of/point of static method in classes JS.

ecmascript-6 class oop javascript
2 Answers

To be able to call the method without creating an instance of the class.

There's some benefit to this. To call an instance method, you would have to create a new instance of the class, and then call the method (it's a two-step process). With static methods, this isn't necessary.

More info here:

Static methods are often utility functions, such as functions to create or clone objects, whereas static properties are useful for caches, fixed-configuration, or any other data you don't need to be replicated across instances.

Static functions are typically referentially-transparent functions. A referentially-transparent function is one that doesn't rely on instance state for its proper functioning. Such a function is easy to reason about, because you don't have to consider anything that is happening outside of the function to understand what it does.

user_1029370

Static methods give the method to the constructor of the class... not the instance. This makes it so you can call ClassName.functionName(param); Instances will still have this function, but it makes it so you can call the function on the class instead of the instance. For example, this doesn't work:

class jump
  doJump() {
    console.log(7);
  }
}
jump.doJump(); // Error
var jumper = new jump();
jumper.jump() // => 7

But this does:

class move {
  static doMove() {
    console.log("works");
  }
}
move.doMove();
var t = new Move()
t.doMove();
user_107737550
Related