Using the never type

The never type was introduced in TypeScript 2.0; it implies a value that never occurs. At first glance, it may seem strange, but it can be used in some situations.

Let's look at what the official documentation says about it:

Suppose that a messaging function that is called within another function specifies the callback.

It would look something like the following code:

const myMessage = (text: string): never => {
    throw new Error(text);
}
const myError = () => Error('Some text here');

Another example would be checking a value that is a string and number at the same time, such as the following:

function neverHappen(someVariable: any) {
    if (typeof someVariable === "string" && typeof someVariable ===
     "number") {
    console.log(someVariable);
    }
}
neverHappen('text');