feat: added dynamic class-name feature via classNames attribute

[vijaypushkin]

Summary

The proposed feature is to add a new syntax for dynamically adding classes to React components. This syntax would be similar to the ngClass directive in Angular, allowing developers to use a classNames attribute to add or remove classes based on certain conditions.

View RFC

How did you test this change?

1. I ran yarn build react/index,react-dom/index --type=UMD
2. Made changes in fixtures/packaging/babel-standalone/dev.html as follows:

    <script type="text/babel">
      const isHovering = false;
      const isDisabled = true;
      ReactDOM.render(
        <button classNames={[
          "primary",
          ["teal", "semi-transparent", isHovering && ["hover", "darken-2"]],
          {loading: true, 'is-disabled': isDisabled},
          undefined,
          false,
          null,
          `custom-class`
        ]}>Click Me!</button>,
        document.getElementById('container')
      );
    </script>

and output was generated as expected

<div id="container">
  <button class="primary teal semi-transparent loading is-disabled custom-class">Click Me!</button>
</div>

Related Issues
#3138, #16705, #20050

[react-sizebot]

Comparing: 559e83a...de18653

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	+0.28%	164.18 kB	164.65 kB	+0.32%	51.78 kB	51.94 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	+0.27%	171.57 kB	172.04 kB	+0.32%	53.99 kB	54.16 kB
facebook-www/ReactDOM-prod.classic.js	+0.19%	570.19 kB	571.26 kB	+0.24%	100.62 kB	100.86 kB
facebook-www/ReactDOM-prod.modern.js	+0.19%	553.93 kB	555.00 kB	+0.24%	97.80 kB	98.04 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable-semver/react-dom/umd/react-dom.production.min.js	+0.29%	164.02 kB	164.49 kB	+0.32%	52.08 kB	52.25 kB
oss-stable/react-dom/umd/react-dom.production.min.js	+0.29%	164.09 kB	164.56 kB	+0.33%	52.10 kB	52.27 kB
oss-stable-semver/react-dom/cjs/react-dom.production.min.js	+0.28%	164.11 kB	164.57 kB	+0.31%	51.76 kB	51.91 kB
oss-stable/react-dom/cjs/react-dom.production.min.js	+0.28%	164.18 kB	164.65 kB	+0.32%	51.78 kB	51.94 kB
oss-experimental/react-dom/umd/react-dom.production.min.js	+0.28%	171.41 kB	171.88 kB	+0.22%	54.27 kB	54.39 kB
oss-stable-semver/react-dom/umd/react-dom.profiling.min.js	+0.27%	173.00 kB	173.47 kB	+0.30%	54.47 kB	54.64 kB
oss-stable/react-dom/umd/react-dom.profiling.min.js	+0.27%	173.07 kB	173.55 kB	+0.30%	54.50 kB	54.66 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	+0.27%	171.57 kB	172.04 kB	+0.32%	53.99 kB	54.16 kB
oss-stable-semver/react-dom/cjs/react-dom.profiling.min.js	+0.27%	173.74 kB	174.21 kB	+0.31%	54.19 kB	54.36 kB
oss-stable/react-dom/cjs/react-dom.profiling.min.js	+0.27%	173.81 kB	174.28 kB	+0.31%	54.21 kB	54.38 kB
oss-experimental/react-dom/cjs/react-dom-unstable_testing.production.min.js	+0.26%	177.78 kB	178.25 kB	+0.26%	56.32 kB	56.47 kB
oss-experimental/react-dom/umd/react-dom.profiling.min.js	+0.26%	180.40 kB	180.87 kB	+0.23%	56.60 kB	56.73 kB
oss-experimental/react-dom/cjs/react-dom.profiling.min.js	+0.26%	181.21 kB	181.68 kB	+0.30%	56.40 kB	56.57 kB

Generated by 🚫 dangerJS against de18653

[github-actions]

This pull request has been automatically marked as stale. If this pull request is still relevant, please leave any comment (for example, "bump"), and we'll keep it open. We are sorry that we haven't been able to prioritize reviewing it yet. Your contribution is very much appreciated.

[github-actions]

This pull request has been automatically marked as stale. If this pull request is still relevant, please leave any comment (for example, "bump"), and we'll keep it open. We are sorry that we haven't been able to prioritize reviewing it yet. Your contribution is very much appreciated.

[github-actions]

Closing this pull request after a prolonged period of inactivity. If this issue is still present in the latest release, please ask for this pull request to be reopened. Thank you!