Where's the list of available functions or API available to me by default in a Jenkinsfile?

Question

I must be bad at searching, but I can't find documentation on what available functions or APIs there are for use in a Jenkinsfile (Groovy syntax).

For example, where is build job: documented? Is that function?

Answer 1

All available steps (includes build-in and plugin supplied) can be found here

The document of build job at here