Static Class that is accessible without creating an instance of it in Typescript

Question

So I am trying to create a class (in TypeScript) that is accessible directly without having to create new instances of it because some classes will change the variables in that class, and other classes need to refer to the changed variables.

Here is my code:

class Auth {
    isAuthenticated: boolean
    constructor(){
        this.isAuthenticated = false;
    }

login(){
    this.isAuthenticated= true;
}

logout(){
    this.isAuthenticated = false;
}

isLoggedIn(){
    return this.isAuthenticated;
}

}

export default new Auth();

if I remove new from export default new Auth(), I get an error:

Value of type 'typeof Auth' is not callable. Did you mean to include 'new'?ts(2348)

How else can I go around this?

for example I want the following scenario

Class A:

import Auth from './auth'

Auth.login()

and another class would do that:

import Auth from './auth'
if(Auth.isLoggedIn){
//do this...
}else
{console.log("not logged in");

If I am using new instances, then the value of that instance will always be false.

Declan Fitzpatrick · Accepted Answer · 2020-11-08 22:52:15Z

1

Just make the methods and variables within the class public and static then you don't need to make an instance of it.

For example

export class Util
{
    public static randomFromTo(from: number, to: number): number
    {
        return Math.floor(Math.random() * (to - from + 1) + from);
    }
}

Can then just do Util.randomFromTo(from, to)

Or use the singleton design pattern

class Singleton {
    public someMethod() { ... }
}

// Using
const x = Singleton.getInstance();
x.someMethod();

answered Nov 8, 2020 at 22:52

Declan Fitzpatrick

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