There are multiple versions of the evalscript, each with somewhat different capabilities and syntax. This is because in parallel with developing Sentinel Hub's capability we are also evolving evalscript. There are several versions available. Currently, the API supports only V3 and OGC still supports all versions of evalscript.
To help you write better and more efficient code, we have prepared a Medium blog post on good scripting practices.
See also the following blog posts on scripting:
- COVID-19 Custom Script Contest, April 6, 2020
- Step into the Beautiful World of Custom Scripts, March 24, 2020
- Water Quality Information for Everyone, March 4, 2020
- Learning Custom Scripts to make Useful and Beautiful Satellite images, September 10, 2019
- Mapping deforestation with Sentinel Hub, Jun 11, 2019
More blog posts can be found on our Sentinel Hub website, where you can find additional useful links and tutorials.