Setting up Typescript with expressjs import error - node.js

Question

I have a folder structure as following
src
--/lib
----/errors
------/notFound.ts
in notFound.ts, I'm exporting this class
export abstract class HttpError extends Error {
abstract statusCode: number;
constructor(message: string) {
super(message);
Object.setPrototypeOf(this, HttpError.prototype);
}
abstract serializeErrors(): { message: string; field?: string }[];
}
export class NotFoundError extends HttpError {
statusCode = 404;
constructor() {
super('Route not found');
Object.setPrototypeOf(this, NotFoundError.prototype);
}
serializeErrors() {
return [{ message: 'The requested route is not Found' }];
}
}
Then in TSconfig.json, I have the path parameter set like this
"paths": {
"#/lib/*" : [
"src/lib/*"
],
"#/routes/*": [
"src/routes/*"
],
"*": [
"node_modules/*"
]
},
When i Import NotFoundError as follows, it results in error
import { NotFoundError } from '#/lib/errors/notFound';
Here's the error.
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:889:15)
at Function.Module._load (internal/modules/cjs/loader.js:745:27)
at Module.require (internal/modules/cjs/loader.js:961:19)
at require (internal/modules/cjs/helpers.js:92:18)
at Object.<anonymous> (/home/tuser/Projects/tpro/src/server/express.ts:5:1)
at Module._compile (internal/modules/cjs/loader.js:1072:14)
at Module._compile (/home/tuser/Projects/tpro/node_modules/source-map-support/source-map-support.js:568:25)
at Module.m._compile (/tmp/ts-node-dev-hook-07042914060113459.js:69:33)
at Module._extensions..js (internal/modules/cjs/loader.js:1101:10)
at require.extensions..jsx.require.extensions..js (/tmp/ts-node-dev-hook-07042914060113459.js:114:20)
[ERROR] 16:40:04 Error: Cannot find module '#/lib/errors/notFound'
I have also tried imports like these
const { NotFoundError } = require('#/lib/errors/notFound')
const NotFoundError = require('#/lib/errors/notFound')
Both result in same error
What am i missing ?

Answer 1

Sorry, I initially wanted to post a comment but I don't have enough rep; instead, I've expanded what I know into a full answer in hopes it helps.
I've recently gone about with setting up Node + TypeScript + Express. The repo I made and was playing around with initially is here, but note that it's undocumented and the auxiliary configs aren't necessarily up to scratch. Also, apologies if the formatting of this answer is really unorthodox, and I hope linking to personal repos is not looked down on.
I'm uncertain if the paths in the tsconfig.json have anything to do with your issue; I've never used them, so I don't know. I would remove them for now.
As a preface, this is an imperfect solution.
For my Node/TypeScript/Express setup I had to do the following:
Set "type": "module" in package.json
Install required packages: > npm install ts-node ts-loader (I'm unsure if both are necessary, I believe they are though)
Add node --es-module-specifier-resolution=node --loader ts-node/esm ./src/server/express.ts (Presuming that express.ts is your entrypoint) as a command to your package.json and check if it works.
With what I understand, this works by specifically invoking ts-node with esm support, and it seems to work on Node 14 LTS and v16.9.1.
The command is rather hacky and will give you warnings about it being an experimental feature. I couldn't find any other solution for myself when (very stubbornly) using ESModules.
I've also used this command to use Webpack with TypeScript and ESM (that is, having a webpack.ts file with ESM imports) to compile TypeScript src files with ESM, as below (in package.json, from here):
"webpack-examples": "node --es-module-specifier-resolution=node --loader ts-node/esm node_modules/webpack-cli/bin/cli.js --config webpack.examples.ts --mode production",

Answer 2

expressjs doesnt support import statements yet. use require for eg const http = require("http");