The Origins of JavaScript

JavaScript is one of the most misunderstood languages in history. Created in just 10 days in May 1995 by Brendan Eich while working at Netscape, it was originally named Mocha, then LiveScript.

It was renamed to JavaScript as a marketing tactic to piggyback on the popularity of Java at the time, despite having almost nothing to do with Java. As the saying goes:

"Java is to JavaScript as Car is to Carpet."

The ECMA Era

To ensure the language didn't remain a proprietary Netscape technology, it was submitted to ECMA International for standardization. This gave birth to ECMAScript.

Key Versions

• ES1 (1997): The first standard.
• ES3 (1999): Added regex, try/catch. The baseline for nearly a decade.
• ES5 (2009): The 'modern' baseline. Strict mode, JSON support, forEach, map, filter.
• ES6 / ES2015 (2015): The Revolution. Classes, Modules, Arrow Functions, Promises, Let/Const. This version changed everything.

How JS Engines Work

JavaScript is a high-level, interpreted (JIT compiled) language. The most famous engine is V8 (Chrome, Node.js), but there's also SpiderMonkey (Firefox) and JavaScriptCore (Safari).

1. Parser: Reads code, checks syntax.
2. AST (Abstract Syntax Tree): Converts code into a tree structure.
3. Interpreter: Converts AST to Bytecode.
4. Profiler: Monitors code execution to find 'hot' code.
5. JIT Compiler: Compiles hot bytecode into highly optimized Machine Code.

This is why modern JS is incredibly fast.