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Using TypeScript Node.js with native ESM

This reference guide shows how to configure a TypeScript Node.js project to work and compile to to native ESM.

Rationale

CommonJS module system was introduced by the Node.js developers due to the lack of the notion of "modules" in the original JavaScript (ECMAScript) language specification at that time. However, nowadays, ECMAScript has a standard module system called ESM — ECMAScript Modules, which is a part of the accepted standard. This way CommonJS could be considered vendor-specific and obsolete/legacy. Hopefully, TypeScript ecosystem now supports the "new" standard.

So the key benefits are:

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Git submodules best practices

Useful commands

— Clone repository with submodules automatically:

git clone --recursive git@github.com:name/repo.git

— Initialize submodules after regular cloning:

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Here's how you could create custom error classes in Node.js using latest ES6 / ES2015 syntax.

I've tried to make it as lean and unobtrusive as possible.

Defining our own base class for errors

errors/AppError.js

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The most optimal way to copy bytes in JavaScript (Uint8Array)

Please read my post in Telegram: Don't use spread operator with byte arrays

Short summary

1. Use target.set(source, offset) MDN
2. Pre-alocate the entire array once
3. Don't use ...spread operator with bytes

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Using Jest with SWC, TypeScript, and ESM

Install dependencies

pnpm add -D jest @jest/globals @types/jest @swc/jest

Create jest.config.js file

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{
  "5.9.10.47:19949": {
    "errors": {
      "LITE_SERVER_UNKNOWN: timeout(during last block synchronization)": 2
    },
    "results": {}
  },
  "5.9.10.15:48014": {
    "errors": {
      "LITE_SERVER_NOTREADY: block is not applied": 38,

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/**
 * This module implements ECMAScript (stage-3) proposal:
 * Promise with resolvers:
 * https://github.com/tc39/proposal-promise-with-resolvers
 *
 * Copyright 2023 Slava Fomin II
 *
 * Permission is hereby granted, free of charge, to any
 * person obtaining a copy of this software and associated
 * documentation files (the “Software”), to deal in the

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server {
    listen 80 default_server;
    root /var/www;

    location / {
        set $cors '';
        set $cors_allowed_methods 'OPTIONS, HEAD, GET';

        if ($http_origin ~ '^https?://(www\.)?example.com$') {
            set $cors 'origin_matched';

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const isValid$ = (
  merge(
    value$.pipe(
      distinctUntilChanged(),
      map(() => undefined),
    ),
    value$.pipe(
      debounceTime(500),
      withLatestFrom(isComplete$),
      filter(([_, isComplete]) => isComplete),

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import { WebApp } from '@grammyjs/web-app';


export function isTwa(): boolean {

  return (
    Boolean(WebApp.initData) ||
    (WebApp.platform !== 'unknown')
  );