[actions] Add Transformation Actions as a class & Add arg type checking lib

[florian-h05]

Fixes #100.

Description

• Adds the Transformation actions to the README.
• Explicitely adds the Transformation actions as a class to provide type defs, JSDoc and arg type checking.
• Adds the typeof-arguments module to allow easy type checking of function arguments (reference also to https://github.com/openhab/openhab-js/issues/176)

Bundle-size increases from 852 KB to 868 KB, which is really not much.

[florian-h05]

@jpg0 Can you review?

[florian-h05]

@digitaldan @jpg0 Can one of you please review so we can get this merged before the 3.4.0 feature freeze?

[jpg0]

I would prefer that the Transformation class is pulled out into it's own file, but whatever, that can be done later.

[jpg0]

Does the failing check matter here? I don't know how the docs system works.

[florian-h05]

Does the failing check matter here? I don't know how the docs system works.

In this case, no I expect that failure. It is caused, because I reference the JSDoc for the Transformation class from the README. The JSDoc it references is not available online yet, it will be when this PR is merged and JSDoc updates.

[florian-h05]

@jpg0 Can we merge then?

[jpg0]

FYI the inverse of this work: transformations using ES6 - has not yet been implemented, and still uses Nashorn.

[florian-h05]

You refer to the JavaScript Transformation service, right? I am aware that it is still using Nashorn, the question is if we need to replace it with a new Transformation service addon, or if using the JS Scripting add-on with https://github.com/openhab/openhab-core/pull/2883 is fine.

[jpg0]

Oh wow, there's lots of progress there that I wasn't aware of. Thanks for the pointer.

[florian-h05]

@jpg0 There are also docs for this (added today): https://github.com/openhab/openhab-docs/pull/1940.

I’ll add a section to our README to document the usage of JS Scripting for transformations.