Exhaustive check for typescript type never
npm install ts-exhaustive-check[![npm version][version-image]][version-url]
[![MIT license][license-image]][license-url]
> Exhaustive check for typescript type never.
This package has a single function called exhaustiveCheck that just checks if a typescript type is of type never.
It will save you one line of code in the default case of switch statements if you have strictNullChecks enabled.
For more information see discriminated-unions and typescript issue 6155.
``
yarn add ts-exhaustive-check
`typescript
import { exhaustiveCheck } from "ts-exhaustive-check";
interface Square {
kind: "square";
size: number;
}
interface Rectangle {
kind: "rectangle";
width: number;
height: number;
}
interface Circle {
kind: "circle";
radius: number;
}
type Shape = Square | Rectangle | Circle;
function area(s: Shape) {
switch (s.kind) {
case "square":
return s.size * s.size;
case "rectangle":
return s.width * s.height;
case "circle":
return Math.PI s.radius s.radius;
default:
return exhaustiveCheck(s);
}
}
`
Without this package the default case in the switch statement would have been this:
`typescript``
function area(s: Shape) {
switch (s.kind) {
...
default:
const _exhaustiveCheck: never = s;
return _exhaustiveCheck;
}
}
[version-image]: https://img.shields.io/npm/v/ts-exhaustive-check.svg?style=flat
[version-url]: https://www.npmjs.com/package/ts-exhaustive-check
[license-image]: https://img.shields.io/github/license/dividab/ts-exhaustive-check.svg?style=flat
[license-url]: https://opensource.org/licenses/MIT