Use the /collab command on Discord to gain access to the OneJS private repo. The repo offers early access to the latest features and fixes that may not yet be available on the Asset Store. An early preview of OneJS V2 is available on branch onejs-v2. It brings major performance improvements, zero-allocation interop, and a new esbuild workflow.
Doc Menu

C# to TS Definition

Out of the box, OneJS provides tons of TS definitions for the Unity ecosystem. UnityEngine, UIElements, Mathematics, to name a few. But there will be times that you'll want to make your own TS definitions for things we haven't covered.

So to make things easier for you, we included an auto converter that can extract TS definitions out of any C# type. You can access it from Unity menu (OneJS -> C# to TSDef Converter). The name you use should be the fully qualified type name. Remember you can use syntax like Foo`1 for generics and Foo+Bar for nested types.

Please note that no such converter is perfect. Ours works better than all the other ones we've tried. It'll get 90% of the work done for you, but you'll still need to make adjustments here and there.