How to get value from static method in typescript?

Question

In my typescript, there is a method added in static. later I am trying to call the same. But getting error... while compile the code. anything wrong with my code? any one help me to understand the static properties in typescript?

Here is my code :

class Car { 
    private distanceRun: number = 0;
    color: string;

    constructor(public hybrid:boolean, color:string="red") {
        this.color = color;
    }

    getGasConsumption():string { 
        return this.hybrid ? "Low" : "High";
    }

    drive(distance:number) {
        return this.distanceRun += distance;
    }

    static horn():string {
        return "HOOONK!";
    }

    get distance():number {
        return this.distanceRun;
    }

}

let newCar = new Car(false);
console.log(newCar.color);
console.log(newCar.horn()); //shows error as Property 'horn' does not exist on type 'Car'..

Live

Suren Srapyan · Accepted Answer · 2018-01-18 05:29:14Z

3

Static members are not attached to the instances of the class. They are attached to the class itself.

You need to call static methods and properties via class, not it's intance - like thisCar.horn().

Live example

You can see, that

class Test {
   get() { 

   }

   static getStatic() {

   }
}

is compiled into this

function Test() {

}

Test.prototype.get = function () {

};

Test.getStatic = function () {

};

From this it is obvious that getStatic is in the Test itself, while get is in the prototype of the Test, which will be referenced from the objects, created via Test function-constructor.

edited Jan 18, 2018 at 5:29

answered Jan 18, 2018 at 5:23

Suren Srapyan

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3 Comments

Jong-Hyen Kim Over a year ago

I was writing same thing

3gwebtrain Over a year ago

@Suren Srapyan - I agreed with you. But what is the reason the class keeping the static like this? any special requirement or reason? what is the correct use of static ? can you please and in your answer?

Suren Srapyan Over a year ago

static should be those fields that are not related to each object. For example, you can have a Point class, which has a static method with name addPoints. This can accept Point objects, add them together and return that. Because this method is related to Points, from the encapsulation view you can make it as static and put in the Point class

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