This feature comes with some limitations.

Types

The following types are supported for properties, and method/signal parameters:

• string
• int/float
• bool
• array
• dictionary
• vector2/3/4/, 2i/3i/4i
• nil

Unsupported types

Some unsupported types are (possibly others):

• Transform3D
• Object
• Basis
• Quaternion

Performance

We put effort into making this feature performant.

Values are represented by their C++ equivalent from std. So, for example if you want to update the player position (Vector3) from GDScript to Javascript every _process(), that is totally fine.

Do note that at a webview refresh rate of 60fps, this is 16ms per frame, so even if the javascript runtime receives updates in a timely manner, the renderer still requires 1 frame to display any visual change you may have caused via the property update.

Arrays and Dictionaries

Both Array and Dictionaries are JSON "stringified" for communication between Godot and Javascript. This means that performance may suffer depending on how complex/big your array or dict is. For 99% of the time, this JSON approach is fine though (<1ms).

However, if you have massive amounts of data to pass around between GDScript and Javascript, please let us know about your use-case. We may be able to introduce fast, dedicated types to accommodate that.