Support chart.js v4.2.0

[bobbingwide]

Chartjs v4.0.1 was released on 14th November 2022.

Requirements

• sb-chart-block should be updated to support this version of chart.js
• I don't yet know if there's going to be a new version of chartjs-adapter-date-fns.
• that may need to be updated as well.

Proposed solution

• Develop PHPUnit tests for sb-chart-block #25
• Apply updates to chart.js v4.0.1
• Re-run PHPUnit tests
• Retest the example blocks in both the block editor and front end.

[bobbingwide]

• Latest version of chart.js is now v4.2.0.
• chart.js v4.2.0 is now an ESM package.
• We need the UMD version of the files, which I downloaded from cdnjs
  • https://cdnjs.cloudflare.com/ajax/libs/Chart.js/4.2.0/chart.umd.js
  • https://cdnjs.cloudflare.com/ajax/libs/Chart.js/4.2.0/chart.umd.min.js
  • this requires a change to the code to enqueue different file names.

[bobbingwide]

chart.js v4.2.0 is now an ESM package.

According to the documentation at https://www.chartjs.org/docs/latest/migration/v4-migration.html, Chart.js became an ESM-only package as of v4.0. But it also states the UMD bundle is still available.

• ESM means ECMAScript Module.
• UMD stands for Universal Module Definition
• All I know is that ESM is different from EMD and the code doesn't work without changes...
• which I don't know how to implement.
• Whereas, if we just load the chart.umd.js or chart.umd.min.js file the JavaScript continues to work.

Re: chart adapter date-fns

• The date-fns adapter supports v4. See https://github.com/chartjs/awesome.
• The GitHub repo https://github.com/chartjs/chartjs-adapter-date-fns is now up to v3.0.0.
• We're currently using v2.0.0
• It seems to work fine.

[bobbingwide]

Note: there seems to be very little difference between chart.umd.js and chart.umd.min.js. Is it worth delivering both?

[bobbingwide]

Chart.js is now at v4.2.1. We should also deliver the matching .map file. It may aid debugging.

[bobbingwide]

Delivered in v1.2.0