cwltool --validate should validate that javascript expressions are valid ES5 expressions

It would be nice if cwltool --validate would report ES5 syntax errors in cwl expressions e.g. running cwltool --validate with this:

cwlVersion: v1.0
requirements:
- class: InlineJavascriptRequirement
inputs:
  - id: parameter
    type: string
    inputBinding:
      valueFrom: $((_ => "test")())
outputs: []
class: CommandLineTool
baseCommand: echo

would report an error, as it uses ES6 syntax.

[tetron]

If eslint or jshint can be easily packed into one file, and the licensing is compatible, it would be even better to add it to the cwltool repo so it can be packaged and distributed as part of cwltool, and read in as a package resource on the fly.

[ThomasHickman]

I’m working on this at the moment