check the type of an object

Question

I have this type defined

export interface Hostel {
    id: String;
}

I want to check if an object is from that type, but there is no way. I have tried with

console.log ('************ ', (typeof result === 'Hostel'));
        console.log ('************ ', (typeof result === Hostel));
        console.log ('************ ', result instanceof Hostel);

I have this error:

'Hostel' only refers to a type, but is being used as a value here.

Does this answer your question? [Interface type check with Typescript](https://stackoverflow.com/questions/14425568/interface-type-check-with-typescript) — Mickael B., Jan 09 '20 at 14:11
Also https://stackoverflow.com/questions/44078205/how-to-check-the-object-type-on-runtime-in-typescript — Orelsanpls, Jan 09 '20 at 14:20

mekwall · Answer 1 · 2020-01-09T14:14:15.340

0

Types (which includes interfaces) are only available during development and compile time and not during runtime. You need to use a class if you want to check the type during runtime.

export class Hostel {
    constructor(public id: String){};
}

const result = new Hostel("foo");

console.log(result instanceof Hostel) // this will return true

edited Jan 09 '20 at 14:14

answered Jan 09 '20 at 14:09

mekwall

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check the type of an object

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