--- title: "oneecma docs" url: https://recursiveai.org/oneecma/docs/ description: "Everything about OneEcma: getting started, host bindings, the error reports and their JSON form, source maps, record and replay, limits, how each built-in…" version: "1.0.0" --- # oneecma docs Everything about OneEcma: getting started, host bindings, the error reports and their JSON form, source maps, record and replay, limits, how each built-in behaves, and how it is checked. ## Start - [Getting started](https://recursiveai.org/oneecma/docs/getting-started/index.md): Install OneEcma for .NET 10, evaluate JavaScript from C#, pass values and functions in, read the error report when a script fails, run untrusted code… - [Overview](https://recursiveai.org/oneecma/docs/overview/index.md): OneEcma is not affiliated with or endorsed by Ecma International. ECMAScript® is a registered trademark of Ecma International. ## Hosting - [Host API](https://recursiveai.org/oneecma/docs/host-api/index.md): The host API is the base layer: [JsExport] bindings, the JSON-Schema tool helper and ScriptEngine.Evaluate are all written with only the public types… - [[JsExport] bindings](https://recursiveai.org/oneecma/docs/js-export/index.md): Mark a type with [JsExport] and a Roslyn generator (the RecursiveAI.OneEcma.Generators package, analyzer-only) writes its binding at build time. There is… - [Runtime, limits and the host](https://recursiveai.org/oneecma/docs/runtime/index.md): This is the contract for code under Builtins/. You can write a built-in area (a constructor, its prototype and its static functions) from this page and… ## Reports - [JSON report](https://recursiveai.org/oneecma/docs/diagnostic-json/index.md): The JSON form of a report. It carries everything the text report shows, as data, so a host, an editor or an agent tool can read it without parsing text.… - [Stack traces](https://recursiveai.org/oneecma/docs/stack-traces/index.md): err.stack follows V8's format and the engine matches Node's output on the differential corpus (testdata/errors/cases.txt, 213 snippets; expected.json is… - [How help lines are chosen](https://recursiveai.org/oneecma/docs/error-help/index.md): The = help: line of a runtime report names the fix. It reads live values from a traced replay and never runs script. - [Syntax error wording](https://recursiveai.org/oneecma/docs/syntax-messages/index.md): The headline of every syntax error and early error is word for word what V8 puts in err.message, so scripts and error-reporting libraries that match on it… - [Auto-repair table](https://recursiveai.org/oneecma/docs/repair-table/index.md): Changes since v1: R012 added (rank 7; every later rank moves down one), R001 also removes a run of adjacent unmatched closers, R007 also erases the… - [Source maps](https://recursiveai.org/oneecma/docs/source-maps/index.md): Reports about minified, bundled or transpiled code point at the source the author wrote. The consumer follows ECMA-426 (https://tc39.es/ecma426/); this… - [Record log and replay](https://recursiveai.org/oneecma/docs/record-log/index.md): A record log holds everything a run took from outside the engine, in order, so the run can be replayed in a fresh engine and give the same values… ## Language and built-ins - [Arrays and iterators](https://recursiveai.org/oneecma/docs/arrays/index.md): Implementation notes for Array, the array iterators, Iterator and the iterator helpers. The algorithms follow ECMA-262 (17th edition) step by step; this… - [Binary data](https://recursiveai.org/oneecma/docs/binary-data/index.md): Normative notes for the binary-data built-ins (ECMA-262 17th edition, clauses 23.2, 23.3, 25.1-25.4). Where the specification leaves room, this file says… - [String, Number, JSON](https://recursiveai.org/oneecma/docs/builtins-string-number-json/index.md): What these built-ins do where ECMA-262 leaves room, the wording of the errors they raise, and where they differ from the reference engine (Node v24.22.1).… - [Collections and Proxy](https://recursiveai.org/oneecma/docs/collections-proxy/index.md): Normative notes for the places where ECMA-262 leaves room or where the engine chooses a mechanism. - [Date](https://recursiveai.org/oneecma/docs/date/index.md): Normative description of Date as implemented in Builtins/Date*.cs: ECMA-262 17th edition 21.4 and Annex B.2.3. - [RegExp](https://recursiveai.org/oneecma/docs/regexp/index.md): Normative description of the pattern parser, compiler, matcher, limits and data tables in src/RecursiveAI.OneEcma/RegExp/. A port reproduces the behaviour… ## Intl and Unicode - [Intl](https://recursiveai.org/oneecma/docs/intl/index.md): Normative description of the engine-internal services behind Intl.NumberFormat, PluralRules, ListFormat, RelativeTimeFormat, DisplayNames, DateTimeFormat… - [Locale data](https://recursiveai.org/oneecma/docs/locale-data/index.md): Normative description of the data the Intl implementation reads: where it comes from, the embedded format, and how to add a locale. A port must be able to… - [Text services](https://recursiveai.org/oneecma/docs/text-services/index.md): Normative description of the three Unicode text services the engine builds on: normalization (UAX #15), collation (UTS #10 with the CLDR root order and… ## Internals - [Syntax tree](https://recursiveai.org/oneecma/docs/ast/index.md): Normative description of what JsParser.Parse produces. A port must reproduce the tree shape, the scope information and the error behavior described here. - [The executor](https://recursiveai.org/oneecma/docs/executor/index.md): Result of a measured spike (a throwaway study project). Two executors were built over the real syntax tree and benchmarked against each other and against… - [Benchmarks](https://recursiveai.org/oneecma/docs/benchmarks/index.md): Throughput is not the product, but it has a floor: real page scripts must stay usable. The floor is roughly at most 2× Jint's time on a small suite. This… ## Reference - [Docs map](https://recursiveai.org/oneecma/docs/docs-map/index.md): These files describe behaviour the specifications leave open, the formats the engine writes, and the choices behind them. They are written so a port to… - [Changelog](https://recursiveai.org/oneecma/docs/changelog/index.md): All notable changes are listed here. The format follows Keep a Changelog and versions follow Semantic Versioning. ## Cookbook - [All recipes](https://recursiveai.org/oneecma/cookbook/index.md): 10 short, task-first recipes with complete code.