We cannot pass a single file via the `module` condition as then
`require( "jquery" )` will not return jQuery but instead the module object
with `default`, `$` & `jQuery` as keys. Instead:
1. For Node.js, detected via the `node` condition:
1. Expose a regular CommonJS version to `require`
2. Expose a tiny wrapper over CommonJS to `import`
2. For bundlers, detected via the `module` condition:
1. Expose a regular ESM version to `import`
2. Expose a tiny wrapper over ESM to `require`
3. If neither Node.js nor bundlers are detected (no `node` or `module`
conditions`):
1. Expose a regular CommonJS version to `require`
2. Expose a regular ESM version to `import`
The reasons for such definitions are as follows:
1. In Node.js, one can synchronously import from a CommonJS file inside of
an ESM one but not vice-versa. To use an ESM file in a CommonJS one,
a dynamic import is required and that forces asynchronicity.
2. In some bundlers CommonJS is not necessarily enabled - e.g. in Rollup without
the CommonJS plugin. Therefore, the ESM version needs to be pure ESM.
However, bundlers allow synchronously calling `require` on an ESM file. This
is possible since bundlers merge the files before they are passed to
the browser to execute and the final bundles no longer contain async import
code.
3. Bare ESM & CommonJS versions are provided to non-Node non-bundler
environments where we cannot assume interoperability between ESM & CommonJS
is supported.
4. Bare versions cannot be supplied to Node or bundlers as projects using both
ESM & CommonJS to fetch jQuery would result in duplicate jQuery instances,
leading to increased JS size and disjoint data storage.
In addition to the above changes, the `script` condition has been dropped. Only
Webpack documents this condition and it's not clear when exactly it's triggered.
Adding support for a new condition can be added later without a breaking change;
removing is not so easy.
The `production` & `development` conditions have been removed as well. They were
not really applied correctly; we'd need to provide both of them to each current
leaf which would double the size of the definition for the `.` & `./slim` entry
points. In jQuery, the only difference between development & production builds
is minification; there are no logic changes so we can pass unminified versions
to all the tooling, expecting minification down the line.
As for the factory entry points:
1. Node.js always gets the CommonJS version
2. Bundlers always get the ESM version
3. Other tools take the ESM version when using `import` and the CommonJS when
using `require`.
The complexity is lower than for the `.` & `./slim` entry points because there's
no default export to handle so Node/bundler wrapper files are not necessary.
Other changes:
* Tests: Change "node:assert" to "node:assert/strict"; the former is deprecated
* Docs: Mention that the CommonJS module doesn't expose named exports
* Tests: Run Node & bundler tests for all the above cases
Fixes gh-5416
Closes gh-5429
Since versions 1.11.0/2.1.0, jQuery has used a module wrapper with one strange
addition - in CommonJS environments, if a global `window` with a `document` was
not present, jQuery exported a factory accepting a `window` implementation and
returning jQuery.
This approach created a number of problems:
1. Properly typing jQuery would be a nightmare as the exported value depends on
the environment. In practice, typing definitions ignored the factory case.
2. Since we now use named exports for the jQuery module version, it felt weird
to have `jQuery` and `$` pointing to the factory instead of real jQuery.
Instead, for jQuery 4.0 we leverage the just added `exports` field in
`package.json` to expose completely separate factory entry points: one for the
full build, one for the slim one.
Exports definitions for `./factory` & `./factory-slim` are simpler than for `.`
and `./slim` - this is because it's a new entry point, we only expose a named
export and so there's no issue with just pointing Node.js to the CommonJS
version (we cannot use the module version for `import` from Node.js to avoid
double package hazard). The factory entry points are also not meant for the Web
browser which always has a proper `window` - and they'd be unfit for an
inclusion in a regular script tag anyway. Because of that, we also don't
generate minified versions of these entry points.
The factory files are not pushed to the CDN since they are mostly aimed
at Node.js.
Closes gh-5293
Summary of the changes:
* define the `exports` field in `package.json`; `jQuery` & `$` are also
exported as named exports in ESM builds now
* declare `"type": "module"` globally except for the `build` folder
* add the `--esm` option to `grunt custom`, generating jQuery as an ECMAScript
module into the `dist-module` folder
* expand `node_smoke_tests` to test the slim & ESM builds and their various
combinations; also, test both jQuery loaded via a path to the file as well
as from module specifiers that should be parsed via the `exports` feature
* add details about ESM usage to the release package README
* run `compare_size` on all built minified files; don't run it anymore on
unminified files where they don't provide lots of value
* remove the remove_map_comment task; SWC doesn't insert the
`//# sourceMappingURL=` pragma by default so there's nothing to strip
Fixes gh-4592
Closes gh-5255
