The type never in Typescript can be used when there is certainty that something will never happen. If you try to assign a value to a variable of type never, the compiler will give you an error:

const a: never = 11; //Type ’number’ is not assignable to type ’never'.

However, you can assign never to a function for example, which will never reach its end or will throw an exception:

function infiniteLoop(): never {
    while (true) {
      console.log("I will never end");
    }
}

function throwAnError(): never {
    throw new Error("Error! Something went wrong");
}

Difference between never and void

A question that comes up is: What is the difference between never and void?

A function that has void as its return, returns nothing while a function has never as its return, returns never.