是否有更简洁的 Typescript 习惯用法用于在运行时未定义值的情况下引发错误？

Question

I'm using dotenv to load some values are runtime. I want to throw an error in the case the value is undefined. Is there a neater way of doing this in Typescript than the following?

    dotenv.config()
    if (process.env.USERNAME == undefined) {
        throw new Error("USERNAME is undefined")
    }
    let username:string = process.env.USERNAME

Answer 1

Node.js has the assert module for purposes like this, though @types/assert fails to declare the functions in this module as type predicates , so the assertions will also need to be done separately using TypeScript at compile-time.

import assert from 'assert';
import dotenv from 'dotenv';

dotenv.config();

assert.notStrictEqual(process.env.USERNAME, undefined, 'USERNAME is undefined');

let username: string = process.env.USERNAME;