Relativity Review Extension requires valid ECMAScript 5.1 for the content of extension scripts. The use of ECMAScript 5.1 ensures that your extension is compatible with major browsers. We recommended that you test your extension in multiple browsers to ensure compatibility.
Neither Relativity nor the Relativity Review application transpiles extension scripts written in ECMAScript 6, TypeScript, or ES Next.
If you want to use features in later versions of ECMAScript or to write your extension in TypeScript, make sure to transpile your extension source code to valid ECMAScript 5.1. Complete this step before uploading it as a resource file to your Relativity application.
For more information, see the following: