Javascript Evolution

Brendan Eich wrote the first version of JavaScript in 10 days back in May 1995. Netscape needed a scripting language for their browser, and they needed it fast. What came out has serious quirks: 0.1 + 0.2 !== 0.3, automatic semicolon insertion that breaks in weird ways, and type coercion where [] + [] = "" while [] + {} = "[object Object]". But it shipped with Netscape Navigator, which meant Microsoft reverse-engineered it for Internet Explorer, which meant every browser had it. By the time anyone thought to ask “should we actually use this?”, the question didn’t matter anymore.

Cross-browser hell and jQuery’s fix

Remember checking navigator.userAgent before every DOM operation? Internet Explorer wanted element.attachEvent, Firefox wanted element.addEventListener, and Safari had opinions about both. Writing cross-browser code meant maintaining parallel implementations for everything. John Resig’s jQuery in 2006 gave us $('#menu').slideDown() that worked everywhere—just a thin wrapper around browser APIs, nothing revolutionary. The real impact was cultural. Before jQuery, web developers avoided client-side scripting when possible. After, it became the default for any interaction. I wrote thousands of lines of jQuery. The code was terrible by modern standards—deeply nested callbacks, global state everywhere, no module system—but we shipped features fast and users didn’t care about architectural purity.

The framework explosion

Google’s Gmail in 2004 showed what AJAX could do. You could update content without page reloads, feel responsive, act like desktop software. Problem: Google didn’t open-source their approach, so everyone invented their own solution. Backbone gave you models and views but nothing else. Knockout had observables. Ember had strong opinions about everything. AngularJS brought dependency injection and two-way binding from backend patterns—clever ideas that made tracking bugs impossible when you had 50 watchers fighting over shared state. React in 2013 felt wrong initially because JSX mixed markup and logic, violating every separation-of-concerns principle we’d learned. One-way data flow created more boilerplate. But the explicit model actually scaled to large applications where Angular’s magic fell apart. Vue showed you could split the difference between convenience and explicitness. Svelte asked why we’re shipping a runtime to users when we could compile it away at build time. The debates got heated because people had invested in mental models around their chosen tools, and switching meant admitting their framework might not be the best approach.

Running it on servers

Ryan Dahl’s Node.js in 2009 let you run the language outside browsers. The pitch was practical: use one language everywhere, share validation logic between client and server, hire people who work across the stack instead of maintaining separate frontend and backend teams. I was skeptical until I built a real-time chat server and realized the event loop model worked well for I/O-heavy servers handling thousands of concurrent connections. No threads, no async/await syntax (this was pre-ES2015), just callbacks and the event loop. The ecosystem was immature—database drivers had bugs, testing tools were basic, deployment was harder than Rails or Django. But npm grew explosively, Express became stable, and resistance faded once the tradeoff of sharing code between client and server proved worthwhile.

Types arrived gradually

Anders Hejlsberg gave a talk in 2012 about adding static types without breaking existing code. We were skeptical. Dynamic typing had been working fine. Previous attempts like Flow and Closure Compiler never gained traction. TypeScript succeeded because you could adopt it incrementally—convert one file at a time, mix typed and untyped code during the transition, and the compiler output stayed readable when debugging. The tooling sold it as much as the type checking. VSCode’s autocomplete using TypeScript’s language server showed what was possible. Rename a function and watch every call site update automatically. Catch errors before running code instead of discovering them in production. By 2020, new projects defaulted to TypeScript, and trying to avoid it felt like swimming upstream.

Modern tooling moves fast

Vite starts dev servers in milliseconds using native ES modules instead of bundling during development. Next.js and Remix blur the line between server and client so thoroughly you sometimes forget which environment your code runs in until something breaks. Bun tries to replace Node, npm, and bundlers with a single binary written in Zig. React Server Components let you write components that only execute on the server, others that only run on the client, and some that do both, with serialization and hydration handled by the runtime. When you understand the model it’s powerful. When you don’t, tracking down bugs becomes painful because you need to reason about multiple execution contexts simultaneously.

Why it persists

JavaScript won through ubiquity rather than technical merit. Browsers run it, developers learn it, libraries target it. That network effect is nearly impossible to overcome. Flash, Silverlight, Dart, even WebAssembly—they all ran into the same barrier. Millions of developers already know JavaScript. Billions of lines of code already use it. The entire web runs on it.

WebAssembly handles performance-critical work well (Figma’s canvas rendering, video codecs, image processing), but for most applications JavaScript is fast enough and easier to work with. ES2015 added arrow functions, promises, and modules. Later versions brought async/await, optional chaining, and nullish coalescing. The TC39 committee learned to ship small updates frequently instead of massive overhauls that break everything.

Is it a good language? Depends what you mean by “good.” It has flaws that will never get fixed because fixing them would break the web. But it’s flexible enough to support multiple programming paradigms, performant enough for most use cases, and has an ecosystem that dwarfs any alternative. Sometimes that’s sufficient.