Several implementations of ES exist, for example, JavaScript, JScript, and Nashorn JavaScript. 2018, Kishori Sharan, Java APIs, Extensions and Libraries: With JavaFX, JDBC, jmod, jlink, Networking, and the Process API, 2nd edition, Apress, →ISBN, page 652:
If you open the tsconfig.json file in the project root folder, you can check which ES version is used in building your application and which ES version is used to target your browser. 2019, Jack Xu, Practical Multiple-Page Apps with ASP.NET Core and Angular Elements: Building Modern Multiple-Page Web Applications Using ASP.NET Core Razor Pages, Angular Elements, WebPack, RXJS, and Mini-SPAs, New York, N.Y.: UniCAD Publishing, →ISBN, page 31:
Work is underway, though, on the next generation of ES, appropriately named ES.Next (ECMA-262 Edition 6), but commonly referred to as ES 6. / As consensus is reached on new ES features, they’re added to the existing draft specification. They’re also listed in ES compatibility tables, such as the ones Mozilla incorporates in much of its documentation, and the exceedingly helpful ECMAScript 6 Compatibility Table. 2015, Shelley Powers, JavaScript Cookbook: Programming the Web, 2nd edition, Sebastopol, Calif.: O’Reilly Media, Inc., →ISBN, page 41: