assert-never
    TypeScript icon, indicating that this package has built-in type declarations

    1.2.1 • Public • Published

    Assert Never npm version

    Helper function for exhaustive checks of discriminated unions in TypeScript.

    Installation

    npm install --save assert-never
    

    Usage

    import {assertNever} from "assert-never";
     
    type A = {type: 'a'};
    type B = {type: 'b'};
    type Union = A | B;
     
    function doSomething(arg: Union) {
      if (arg.type === 'a') {
        return something;
      }
     
      if (arg.type === 'b') {
        return somethingElse;
      }
     
      // TS will error if there are other types in the union
      // Will throw an Error when called at runtime. Use `assertNever(arg, true)`
      // instead to fail silently.
      return assertNever(arg);
    }

    Install

    npm i assert-never

    DownloadsWeekly Downloads

    832,946

    Version

    1.2.1

    License

    MIT

    Unpacked Size

    4.17 kB

    Total Files

    5

    Last publish

    Collaborators

    • aikoven