This repository provides ECMAScript compatibility tables for JavaScript engines, browsers, and compilers. It ingests test definitions (embedded as commented JavaScript code) and expected results per engine version, then builds static HTML pages via Node.js scripts. The data covers ES5 through ES2025+ proposals, Intl, and non-standard features, with thousands of subtests mapped to hundreds of engine versions. The codebase is primarily a data pipeline with a build system (using cheerio for HTML generation) and optional test runners that execute tests against real engines (e.g., Duktape, GraalVM) to validate or update results. The output is the well-known kangax.github.io/compat-table static site. While the data is meticulously maintained, the repository is not a reusable library or application; it is a specialized data project with moderate reproducibility due to reliance on external engine binaries and outdated dependencies like jQuery 1.12.