> ## Documentation Index
> Fetch the complete documentation index at: https://docs.solved.gg/llms.txt
> Use this file to discover all available pages before exploring further.

# ES feature matrix

> Living ECMAScript feature matrix for scripty pre-v0.0.1 (ES2026 pin).

# ES feature matrix

Status vocabulary: [Status vocabulary](/scripty/v0.0.1-dev/reference/status-vocabulary).

**Edition pin:** ECMAScript **2026** (17th edition) — [Sources](/scripty/v0.0.1-dev/reference/sources) · HTML [17.0](https://262.ecma-international.org/17.0/).\
**Oracle:** Test262 (in-scope).\
**Update rule:** change status only with tests + PR. Do not claim a newer edition without re-pin.

> Rows start honest for a greenfield engine. `partial` reflects early scripty smokes where applicable.

## Syntax & language

| Feature                                | Status        | Notes / tests                                                  |
| -------------------------------------- | ------------- | -------------------------------------------------------------- |
| Lexer / tokenizer                      | `partial`     | `src/syntax/lexer.zig`                                         |
| Parser (statements / expressions)      | `partial`     | `src/syntax/parser.zig`                                        |
| Strict mode                            | `partial`     | Default/strict edge cases incomplete                           |
| Classes (methods, heritage, static)    | `unsupported` | —                                                              |
| Private fields / methods / accessors   | `unsupported` | —                                                              |
| `async` / `await`                      | `partial`     | Promises exist; full async fn semantics TBD                    |
| Generators / `yield`                   | `unsupported` | —                                                              |
| Async generators                       | `unsupported` | —                                                              |
| Arrow functions                        | `partial`     | Smoke coverage only                                            |
| Destructuring                          | `partial`     | Incomplete                                                     |
| Rest / spread                          | `partial`     | Incomplete                                                     |
| Default parameters                     | `partial`     | Incomplete                                                     |
| Optional chaining `?.`                 | `unsupported` | —                                                              |
| Nullish coalescing `??`                | `unsupported` | —                                                              |
| Logical assignment `&&=` `\|\|=` `??=` | `unsupported` | —                                                              |
| Numeric separators                     | `unsupported` | —                                                              |
| BigInt literals                        | `unsupported` | —                                                              |
| Template literals (incl. tagged)       | `partial`     | Incomplete                                                     |
| `for-of` / `for-await-of`              | `unsupported` | —                                                              |
| `using` / explicit resource management | `unsupported` | In-scope: reached Stage 4 and is in ES2026 (ECMA-262 17th ed.) |

## Types & values

| Feature                                      | Status        | Notes / tests             |
| -------------------------------------------- | ------------- | ------------------------- |
| undefined / null / boolean / number / string | `partial`     | `src/vm/values.zig`       |
| Object / Array                               | `partial`     | Simple property model     |
| Function                                     | `partial`     | Host + JS functions       |
| Symbol                                       | `unsupported` | —                         |
| BigInt                                       | `unsupported` | —                         |
| Property attributes                          | `partial`     | Not full descriptor model |
| Prototypes                                   | `partial`     | —                         |
| Exotic objects path                          | `unsupported` | —                         |

## Execution & runtime semantics

| Feature                      | Status      | Notes / tests                                     |
| ---------------------------- | ----------- | ------------------------------------------------- |
| Bytecode + interpreter       | `partial`   | `src/vm/*`                                        |
| Lexical environments         | `partial`   | —                                                 |
| `this` binding               | `partial`   | —                                                 |
| `new` / constructors         | `partial`   | —                                                 |
| try / catch / finally        | `partial`   | —                                                 |
| Exceptions / `Error` throw   | `partial`   | —                                                 |
| Promises + jobs              | `supported` | `testdata/smoke/promise_then.js`, microtask order |
| Microtask ordering vs timers | `supported` | `testdata/smoke/microtask_order.js`               |

## Built-in groups (summary)

Detail: [Built-ins](/scripty/v0.0.1-dev/es/builtins).

| Group                               | Status                    | Notes                               |
| ----------------------------------- | ------------------------- | ----------------------------------- |
| Object / Function / Array basics    | `partial`                 | —                                   |
| String / Number / Boolean / Math    | `partial` / `unsupported` | Math largely missing                |
| Date / JSON / Error                 | `unsupported` / `partial` | —                                   |
| Promise (built-in surface)          | `partial`                 | then/jobs; not full static API      |
| Symbol / Map / Set / Weak\*         | `unsupported`             | —                                   |
| RegExp                              | `unsupported`             | —                                   |
| TypedArray / ArrayBuffer / DataView | `unsupported`             | —                                   |
| Proxy / Reflect                     | `unsupported`             | —                                   |
| Iterator helpers (ES2025+)          | `unsupported`             | —                                   |
| Set methods (ES2025+)               | `unsupported`             | —                                   |
| Intl                                | `unsupported`             | Scope decision: implement or refuse |

## Modules (language)

| Feature                             | Status        | Notes / tests            |
| ----------------------------------- | ------------- | ------------------------ |
| ESM parse / link / evaluate (local) | `partial`     | Relative only; smokes    |
| Cyclic modules                      | `unsupported` | —                        |
| Top-level await                     | `unsupported` | —                        |
| Import attributes                   | `unsupported` | As required by pin       |
| `import.meta`                       | `partial`     | Minimal / host-dependent |

## GC

| Feature                           | Status        | Notes                                               |
| --------------------------------- | ------------- | --------------------------------------------------- |
| Precise STW mark–sweep + freelist | `partial`     | Design in repo `docs/vm-gc.md`; auto collect exists |
| Incremental GC                    | `unsupported` | Post language-gate OK                               |

## Annex B (opt-in)

| Feature                              | Status        | Policy                             |
| ------------------------------------ | ------------- | ---------------------------------- |
| Annex B syntax/semantics (aggregate) | `unsupported` | Opt-in per concrete row when added |

## Exit bar for I1

All **in-scope** rows above (and their detailed built-in rows) must be `supported` or `dogfooded`, with Test262 blockers at zero. See [Scope](/scripty/v0.0.1-dev/es/scope).


## Related topics

- [Status vocabulary](/scripty/v0.0.1-dev/reference/status-vocabulary.md)
- [ES phases](/scripty/v0.0.1-dev/es/phases.md)
- [ES scope](/scripty/v0.0.1-dev/es/scope.md)
- [I1 — ES Engine](/scripty/v0.0.1-dev/es/index.md)
- [ES built-ins](/scripty/v0.0.1-dev/es/builtins.md)