Adding support for ECMAScript 2015 (ES6)

[mayacoda]

Hello all!

Would it be possible to bump the ECMAScript version specified for Expressions from 5.1 to 6.0? ES6 offers many new features that are becoming common knowledge and are widely available in modern browsers. Considering that JavaScript is not "native" to most CWL authors, they tend to find solutions for expressions without regard (or knowledge) about the version of the language they're using.

For example, I've seen features like Set, Array.from() or backticks for template strings used in expressions, because they are the most elegant way to solve the problem. Of course, these tools fail during execution because these features aren't in ES5.

Is there any particular reason why only ES5 is supported? Is there any plan to update the version in the future?

• [ ] implement cwltool:ECMAScriptVersionRequirement in cwltool for v1.0 documents
• [ ] add conformances tests using ECMAScript 6 constructs to cwl-v1.1
• [ ] modify cwltool to adjust the Javascript linting to match the cwlVersion and cwltool:ECMAScriptVersionRequirement (if present)

[kmhernan]

Would the use strict issue come up? https://www.nczonline.net/blog/2016/10/the-ecmascript-2016-change-you-probably-dont-know/

[ivanbatic]

It would technically be a backwards incompatibility, but I think it is extremely unlikely to come up as a problem. Even if somebody has an issue, it can easily be parsed and auto-fixed.

[tetron]

Discussion from 27 Nov 2018:

For cwl v1.0 documents, introduce a cwltool requiremement, something like:

requirements:
  cwltool:ECMAScriptVersionRequirement:
    ecmascriptVersion: 6

For cwl v1.1 documents: ECMAScript 6 is the default for all expressions.

[mr-c]

Which versions of ECMAScript will we require engines to support?

Also, should we allow them to support additional version beyond that?

https://en.wikipedia.org/wiki/ECMAScript