Difference between static and normal function inside a class

Question

I have defined my class in this manner

class className {
  constructor() {

  }

  static myStaticFunction() {
    console.log("myStaticFunction")
  }

  normalFunction() {
    console.log("normalFunction")
  }
}

module.exports = className

I know normalFunction can be called using instance whereas static function can be called without the instance. But I need to know what is the difference between above two function declaration?

Thank you!!!

score 2 · Answer 1 · answered Feb 13 '19 at 06:20

When a function is called from the class itself it is called a static function where as the normal function is called on the instance of the class

For example

class className {
  constructor() {}

  static myStaticFunction() {
    console.log("myStaticFunction")
  }

  normalFunction() {
    myStaticFunction() // here myStaticFunction is called from same class
    console.log("normalFunction")
  }
}

module.exports = className

In some other js file

import * as class1 from './class';
class className2 {
      constructor() {}

        someFunction() {
        class1 .normalFunction(); //calling class function
        console.log("normalFunction")
      }
    }

    module.exports = className2

Pranay Rana · Answer 2 · 2019-02-13T10:13:58.353

Static function - is not entitled to any object instance. Which means that function is accessible with out instance and it also cannnot access any instance data. Basically it helps to expose functionality which kind of util.

As MDN describes it, “Static methods are called without instantiating their class and are also not callable when the class is instantiated. Static methods are often used to create utility functions for an application.” In other words, static methods have no access to data stored in specific objects.

Example : Math.Sqrt(val) - is util function.

And Static function must need be pure functions, that doesnt modify the object data and provides utility.

so here how it works

class className {
  instanceCounter = 0;
  staticCounter = 0;
  constructor() {

  }

  static myStaticFunction() {
    this.staticCounter++;
    console.log("myStaticFunction"+ staticCounter);
  }

  normalFunction() {
    this.instanceCounter++;
    console.log("normalFunction" + instanceCounter);
  }
}

now if i make call

   //for static   
   className.myStaticFunction();//print 1
   className.myStaticFunction();//print 2

   //for instace 
   new className().normalFunction();//print 1
   new className().normalFunction();//print 1

Difference between static and normal function inside a class

2 Answers2