Shrugging it off as just being large because it contains the "standard library" ignores that many JS language features necessarily use native objects like symbols or promises, which can't be entirely implemented in just JavaScript alone, so they are intrinsic rather than being standard library components, akin to Go builtins rather than the standard library. In fact, in
actual environments, the browser and/or Node.JS provide the
actual standard library, including things like fetch, sockets, compression codecs, etc. Even ignoring almost all of those bits though, the spec is absolutely enormous, because JavaScript has:
- Regular expressions - not just in the "standard library" but in the syntax.
- An entire module system with granular imports and exports
- Three different ways to declare variables, two of which create temporal dead zones
- Classes with inheritance, including private properties
- Dynamic properties (getters and setters)
- Exception handling
- Two different types of closures/first class functions, with different binding rules
- Async/await
- Variable length "bigint" integers
- Template strings
- Tagged template literals
- Sparse arrays
- for in/for of/iterators
- for await/async iterators
- The with statement
- Runtime reflection
- Labeled statements
- A lot of operators, including bitwise operators and two sets of equality operators with different semantics
- Runtime code evaluation with eval/Function constructor
And honestly it's only scratching the surface, especially of modern ECMAScript.
A language spec is necessarily long. The JS language spec, though, is so catastrophically long that it is a bit hard to load on a low end machine or a mobile web browser. It's on another planet.