---
title: "The JavaScript Ecosystem is Delightfully Weird"
description: "The post explains why the JavaScript ecosystem is “delightfully weird,” arguing that its defining feature is not JavaScript’s oddness but the layers of transformation surrounding it. Bundlers first changed source boundaries by minimizing, tree-shaking, code-splitting, and producing executable files different from those developers wrote; CoffeeScript, Babel, TypeScript, JSX, Svelte, and esbuild extended that pattern. Frameworks and tools also make the ecosystem a “Big Tent,” allowing imports of CSS or PNG files and adding semantics outside ECMAScript, such as Svelte’s reactive labels and TypeScript annotations. React Server Components push this further: “use server” and “use client” are valid no-op statements whose placement changes code meaning, while RSC compiles into a stream of tagged JSON and depends on bundlers. The post presents this cooperation among languages, frameworks, routers, and bundlers—including the server/client interaction demonstrated in Dan Abramov’s React talk—as profound and beneficial, especially for geographically distributed application styles."
---

# The JavaScript Ecosystem is Delightfully Weird

[Fly.io](https://yomu.fyi/company/fly-io) · May 11, 2023

**Type:** Explainer

## Summary

The post explains why the JavaScript ecosystem is “delightfully weird,” arguing that its defining feature is not JavaScript’s oddness but the layers of transformation surrounding it. Bundlers first changed source boundaries by minimizing, tree-shaking, code-splitting, and producing executable files different from those developers wrote; CoffeeScript, Babel, TypeScript, JSX, Svelte, and esbuild extended that pattern. Frameworks and tools also make the ecosystem a “Big Tent,” allowing imports of CSS or PNG files and adding semantics outside ECMAScript, such as Svelte’s reactive labels and TypeScript annotations. React Server Components push this further: “use server” and “use client” are valid no-op statements whose placement changes code meaning, while RSC compiles into a stream of tagged JSON and depends on bundlers. The post presents this cooperation among languages, frameworks, routers, and bundlers—including the server/client interaction demonstrated in Dan Abramov’s React talk—as profound and beneficial, especially for geographically distributed application styles.

## Context

The post examines why JavaScript development continues to rely on transpilers and bundlers even as the language and its implementations have improved. It attributes the ecosystem’s unusual character to successive layers that transform source code, extend language semantics, and connect browser, server, framework, and asset workflows.

## Approach / What changed

It traces the ecosystem from bundling, CoffeeScript, ECMAScript 6, Babel, and emscripten through TypeScript, JSX, Svelte, asset imports, and React Server Components. It uses “use server” and “use client,” tagged JSON output, and Dan Abramov’s alternate-dimension React demonstration to show how bundlers and routers participate in behavior that resembles changes to the language itself.

## Takeaways

- Bundling can minimize, tree-shake, code-split, and transform multiple input sources into executable JavaScript that differs from the code developers wrote; sourcemaps help bridge that gap.
- The JavaScript ecosystem treats extensions beyond ECMAScript as normal, including TypeScript annotations, JSX, Svelte’s reactive labels, and bundler imports of CSS or PNG files.
- React Server Components use “use server” and “use client” directives to alter code meaning and compile output into a stream of tagged JSON, requiring cooperation from routers and bundlers.

**Tags:** [JavaScript](https://yomu.fyi/topic/javascript), [React](https://yomu.fyi/topic/react), [TypeScript](https://yomu.fyi/topic/typescript)

- Source: [Fly.io](https://fly.io/blog/js-ecosystem-delightfully-wierd)
- Source URL: https://fly.io/blog/js-ecosystem-delightfully-wierd
- Ingested by Yomu: 2026-09-03T01:24:00.468Z

[Read original post](https://fly.io/blog/js-ecosystem-delightfully-wierd)