The Language That Runs the Internet Was Built in 10 Days (And We're Still Paying for It)

The Deadline

May 1995. Netscape was at war with Microsoft for control of the web browser market. Marc Andreessen, Netscape's co-founder, wanted a scripting language embedded in the browser — something simple that could make web pages interactive.

He hired Brendan Eich with a specific promise: you'll get to build a language based on Scheme, a elegant functional programming language. Then management changed their minds. They'd just signed a deal with Sun Microsystems. The new directive: make it look like Java.

Eich had 10 days.

The 10-Day Sprint

From May 6 to May 15, 1995, Eich locked himself away and built a prototype of what would become JavaScript. In just over a week, he created: the core syntax, functions as first-class objects, prototypal inheritance (borrowed from Self), event handling for the browser, and dynamic typing.

The result was a Frankenstein language — Java's syntax stapled onto Scheme's functional core, with Self's prototype system bolted on. It was messy, inconsistent, and full of quirks that would haunt developers for decades.

It was also brilliant.

The Quirks We're Still Living With

Those 10 days produced some of JavaScript's most infamous behaviors. Type coercion that makes no sense on the surface: adding an empty array to an empty object produces the number zero. Comparing null to undefined returns true with double equals but false with triple equals.

These weren't bugs — they were trade-offs made under impossible time pressure. Eich had to make hundreds of design decisions in 10 days. Some were inspired. Others were "I'll fix this later" moments that never got fixed because backward compatibility became sacred.

The web was growing too fast. You can't break the language that runs every website on earth. Every quirk, every inconsistency, every "wat" moment in JavaScript — they're permanent. Archaeological layers of a language built in a sprint.

The Name Game

JavaScript was originally called Mocha. Then LiveScript. Then, in a marketing decision that caused decades of confusion, Netscape renamed it JavaScript to ride the hype wave of Java.

The languages have almost nothing in common. Java is statically typed, class-based, and compiled. JavaScript is dynamically typed, prototype-based, and interpreted. But the name stuck, and twenty-five years later, people still confuse them in job interviews.

Eich later said the name was "a marketing ploy" that he regretted. But by then, JavaScript was everywhere.

The Redemption Arc

For years, JavaScript was dismissed as a toy language. "Real" programmers used Java, C++, or Python. JavaScript was for making buttons change color when you hovered over them.

Then came three revolutions.

First: AJAX (2005). Gmail and Google Maps proved that JavaScript could build real applications in the browser. Second: Node.js (2009). Ryan Dahl put JavaScript on the server, and suddenly one language could run everywhere. Third: the modern ecosystem — React, TypeScript, Next.js, Deno — that transformed JavaScript from a scripting language into a platform.

The language built in 10 days now powers 98% of websites, runs server infrastructure, builds mobile apps, and even controls robots.

The Lesson

JavaScript's story is a reminder that great things don't need perfect beginnings. Sometimes the constraints — the impossible deadlines, the contradictory requirements, the "make it look like Java" mandates — produce something that's messy, human, and ultimately unstoppable.

Brendan Eich didn't set out to build the most widely-used programming language in history. He set out to survive a 10-day deadline. The language carries the scars of that sprint in every quirk and inconsistency. But it also carries something else: the adaptability, the flexibility, and the sheer stubbornness that made it the language of the web.

The best tools aren't the ones that are designed perfectly. They're the ones that refuse to die.