Clone document on addStatic.

[aljones15]

This seems like the easiest solution to the document mutation issue.
If we don't want a dep we could use JSON.parse(JSON.stringify(document)) as the jsonld doc should be just JSON.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.40%. Comparing base (9ef1abd) to head (b0bc444).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #14      +/-   ##
==========================================
+ Coverage   98.27%   98.40%   +0.12%     
==========================================
  Files           2        2              
  Lines         116      125       +9     
==========================================
+ Hits          114      123       +9     
  Misses          2        2              

Files	Coverage Δ
lib/JsonLdDocumentLoader.js	98.33% <100.00%> (+0.13%)	⬆️

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[aljones15]

@dlongley structuredClone works, but not in node <= 16 came in to node in 17 according to the page you linked to.

[dlongley]

Thanks!

[dlongley]

We should drop the testing for node 16 and bump the suggestion in the package.json (if any) to node 18+.

[aljones15]

@dlongley while bumping engines we had previously agreed is not major is adding a new method that is node >= 17 only and only supported in somewhat recent browsers breaking and hence a major change?

[dlongley]

Given our package.json "node recommendation" policy, it's not a breaking change. We've just gotten behind on upgrading this particular package's expected node value here. We only support LTS+. So we could do the node >= 18 bump in a separate PR and release first, but it would still be a non-breaking release. Since there's no real difference there other than churn, let's roll this all together.

The supported browsers and node versions are "current" and LTS+, and think we're good there for the structuredClone feature:

https://caniuse.com/?search=structuredClone

If people need to polyfill this in old browsers I imagine they're already doing so in their build pipelines or should be. As a matter of policy, our individual libraries do not provide support for legacy platforms.

[davidlehn]

• Just to check, the speed and memory hit on this is ok? I imagine in most use cases no one one notice. But there's also no choice for those rare use cases with huge resources. "Use another loader" is a choice of course.
• "engine" spec issues aside, the definite newer API usage here could break user code running in 16.x (for whatever legacy reasons that is being used). Are you all sure you want to do that?

[davidlehn]

• "engine" spec issues aside, the definite newer API usage here could break user code running in 16.x (for whatever legacy reasons that is being used). Are you all sure you want to do that?

At a minimum, I think the changelog should note support or a polyfill for structuredClone is required and mention whatever version of Node.js that is.

[davidlehn]

I'm not convinced this is needed, but we'll try it out, and adjust the API if needed.