This PR updates the `jiti` dependency we use for plugin loading to the
latest stable release.
## Test Plan
This was relying on integration tests which contains example of
TypeScript configs. It's also rebased to include the new examples from
https://github.com/tailwindlabs/tailwindcss/pull/15041.
We noticed that in the current alpha 34 release, the `package.json` file
of the `@tailwindcss/node` package only defines `tailwindcss` as a dev
dependency. This makes it very easy for version mismatches to happen
when a v3 version (or an earlier v4 alpha for that matter) was installed
in the same project:
```json
{
"name": "@tailwindcss/node",
"version": "4.0.0-alpha.34",
"description": "A utility-first CSS framework for rapidly building custom user interfaces.",
"license": "MIT",
"repository": {
"type": "git",
"url": "https://github.com/tailwindlabs/tailwindcss.git",
"directory": "packages/@tailwindcss-node"
},
"bugs": "https://github.com/tailwindlabs/tailwindcss/issues",
"homepage": "https://tailwindcss.com",
"files": [
"dist/"
],
"publishConfig": {
"provenance": true,
"access": "public"
},
"exports": {
".": {
"types": "./dist/index.d.ts",
"import": "./dist/index.mjs",
"require": "./dist/index.js"
},
"./require-cache": {
"types": "./dist/require-cache.d.ts",
"default": "./dist/require-cache.js"
},
"./esm-cache-loader": {
"types": "./dist/esm-cache.loader.d.mts",
"default": "./dist/esm-cache.loader.mjs"
}
},
"devDependencies": {
"tailwindcss": "4.0.0-alpha.34"
},
"dependencies": {
"enhanced-resolve": "^5.17.1",
"jiti": "^2.0.0-beta.3"
},
"scripts": {
"build": "tsup-node",
"dev": "pnpm run build -- --watch"
}
}
```
Furthermore, we were trying to fix issues where our integration test
setup could not install `tailwindcss@3` because of how we did pnpm
overrides.
This PR fixes this by:
- Ensuring every client that calls into `tailwindcss` core marks it as a
version-pinned dependency. You are still required to install
`tailwindcss` in your project along side a client (e.g.
`@tailwindcss/vite`) but we now only use your installed version for
importing the respective `.css` files. For the core logic, we are now
requiring each package to use `tailwindcss` at the same version. This
should help resolve issues like
https://github.com/tailwindlabs/tailwindcss/discussions/14652
- We tried to eliminate the dependency on `tailwindcss` from the
`@tailwindcss/upgrade` package. Unfortunately this is not possible to do
right now because we need to load the CSS files from v4 to create the
right environment. In a future version we could bundle the required CSS
files with `@tailwidncss/upgrade` but it doesn't seem necessary for now.
- We then changed our integration test overrides to only override the
`tailwindcss` package that are dependencies of the known list of
packages that we have `tailwindcss` dependencies on: `@tailwindcss/node`
and `@tailwindcss/upgrade`. This ensures that we can install v3 of
`tailwindcss` in the integration tests and it will work. Something we
want to do for some upgrade tests.
# Test plan
Integration work again. Furthermore we added a quick setup with the CLI
using the local tarballs and ensured it works:
```bash
pnpm init
pnpm install ../../tailwindcss/dist/tailwindcss-cli.tgz
pnpm install ../../tailwindcss/dist/tailwindcss.tgz
echo '@import "tailwindcss";' > index.css
echo '<div class="underline"></div>' > index.html
pnpm tailwindcss -i index.css -o out.css
cat out.css
```
This PR brings `@import` resolution into Tailwind CSS core. This means
that our clients (PostCSS, Vite, and CLI) no longer need to depend on
`postcss` and `postcss-import` to resolve `@import`. Furthermore this
simplifies the handling of relative paths for `@source`, `@plugin`, or
`@config` in transitive CSS files (where the relative root should always
be relative to the CSS file that contains the directive). This PR also
fixes a plugin resolution bug where non-relative imports (e.g. directly
importing node modules like `@plugin '@tailwindcss/typography';`) would
not work in CSS files that are based in a different npm package.
### Resolving `@import`
The core of the `@import` resolution is inside
`packages/tailwindcss/src/at-import.ts`. There, to keep things
performant, we do a two-step process to resolve imports. Imagine the
following input CSS file:
```css
@import "tailwindcss/theme.css";
@import "tailwindcss/utilities.css";
```
Since our AST walks are synchronous, we will do a first traversal where
we start a loading request for each `@import` directive. Once all loads
are started, we will await the promise and do a second walk where we
actually replace the AST nodes with their resolved stylesheets. All of
this is recursive, so that `@import`-ed files can again `@import` other
files.
The core `@import` resolver also includes extensive test cases for
[various combinations of media query and supports conditionals as well
als layered
imports](https://developer.mozilla.org/en-US/docs/Web/CSS/@import).
When the same file is imported multiple times, the AST nodes are
duplicated but duplicate I/O is avoided on a per-file basis, so this
will only load one file, but include the `@theme` rules twice:
```css
@import "tailwindcss/theme.css";
@import "tailwindcss/theme.css";
```
### Adding a new `context` node to the AST
One limitation we had when working with the `postcss-import` plugin was
the need to do an additional traversal to rewrite relative `@source`,
`@plugin`, and `@config` directives. This was needed because we want
these paths to be relative to the CSS file that defines the directive
but when flattening a CSS file, this information is no longer part of
the stringifed CSS representation. We worked around this by rewriting
the content of these directives to be relative to the input CSS file,
which resulted in added complexity and caused a lot of issues with
Windows paths in the beginning.
Now that we are doing the `@import` resolution in core, we can use a
different data structure to persist this information. This PR adds a new
`context` node so that we can store arbitrary context like this inside
the Ast directly. This allows us to share information with the sub tree
_while doing the Ast walk_.
Here's an example of how the new `context` node can be used to share
information with subtrees:
```ts
const ast = [
rule('.foo', [decl('color', 'red')]),
context({ value: 'a' }, [
rule('.bar', [
decl('color', 'blue'),
context({ value: 'b' }, [
rule('.baz', [decl('color', 'green')]),
]),
]),
]),
]
walk(ast, (node, { context }) => {
if (node.kind !== 'declaration') return
switch (node.value) {
case 'red': assert(context.value === undefined)
case 'blue': assert(context.value === 'a')
case 'green': assert(context.value === 'b')
}
})
```
In core, we use this new Ast node specifically to persist the `base`
path of the current CSS file. We put the input CSS file `base` at the
root of the Ast and then overwrite the `base` on every `@import`
substitution.
### Removing the dependency on `postcss-import`
Now that we support `@import` resolution in core, our clients no longer
need a dependency on `postcss-import`. Furthermore, most dependencies
also don't need to know about `postcss` at all anymore (except the
PostCSS client, of course!).
This also means that our workaround for rewriting `@source`, the
`postcss-fix-relative-paths` plugin, can now go away as a shared
dependency between all of our clients. Note that we still have it for
the PostCSS plugin only, where it's possible that users already have
`postcss-import` running _before_ the `@tailwindcss/postcss` plugin.
Here's an example of the changes to the dependencies for our Vite client
✨ :
<img width="854" alt="Screenshot 2024-09-19 at 16 59 45"
src="https://github.com/user-attachments/assets/ae1f9d5f-d93a-4de9-9244-61af3aff1237">
### Performance
Since our Vite and CLI clients now no longer need to use `postcss` at
all, we have also measured a significant improvement to the initial
build times. For a small test setup that contains only a hand full of
files (nothing super-complex), we measured an improvement in the
**3.5x** range:
<img width="1334" alt="Screenshot 2024-09-19 at 14 52 49"
src="https://github.com/user-attachments/assets/06071fb0-7f2a-4de6-8ec8-f202d2cc78e5">
The code for this is in the commit history if you want to reproduce the
results. The test was based on the Vite client.
### Caveats
One thing to note is that we previously relied on finding specific
symbols in the input CSS to _bail out of Tailwind processing
completely_. E.g. if a file does not contain a `@tailwind` or `@apply`
directive, it can never be a Tailwind file.
Since we no longer have a string representation of the flattened CSS
file, we can no longer do this check. However, the current
implementation was already inconsistent with differences on the allowed
symbol list between our clients. Ideally, Tailwind CSS should figure out
wether a CSS file is a Tailwind CSS file. This, however, is left as an
improvement for a future API since it goes hand-in-hand with our planned
API changes for the core `tailwindcss` package.
---------
Co-authored-by: Jordan Pittman <[email protected]>
<!--
👋 Hey, thanks for your interest in contributing to Tailwind!
**Please ask first before starting work on any significant new
features.**
It's never a fun experience to have your pull request declined after
investing a lot of time and effort into a new feature. To avoid this
from happening, we request that contributors create an issue to first
discuss any significant new features. This includes things like adding
new utilities, creating new at-rules, or adding new component examples
to the documentation.
https://github.com/tailwindcss/tailwindcss/blob/master/.github/CONTRIBUTING.md
-->
```ts
// error: can't find `@tailwindcss/node` types file
import { compile } from '@tailwindcss/node';
```
Tailwind V3 used [jiti](https://github.com/unjs/jiti/) to allow
importing of TypeScript files for the config and plugins. This PR adds
the new Jiti V2 beta to our `@tailwindcss/node` and uses it if a native
`import()` fails. I added a new integration test to the CLI config
setup, to ensure it still works with our module cache cleanup.
<!--
👋 Hey, thanks for your interest in contributing to Tailwind!
**Please ask first before starting work on any significant new
features.**
It's never a fun experience to have your pull request declined after
investing a lot of time and effort into a new feature. To avoid this
from happening, we request that contributors create an issue to first
discuss any significant new features. This includes things like adding
new utilities, creating new at-rules, or adding new component examples
to the documentation.
https://github.com/tailwindcss/tailwindcss/blob/master/.github/CONTRIBUTING.md
-->
Co-authored-by: Adam Wathan <[email protected]>
In Tailwind v4 the CSS file is the main entry point to your project and
is generally configured via `@theme`. However, given that all v3
projects were configured via a `tailwind.config.js` file we definitely
need to support those. This PR adds support for loading existing
Tailwind config files by adding an `@config` directive to the CSS —
similar to how v3 supported multiple config files except that this is
now _required_ to use a config file.
You can load a config file like so:
```
@import "tailwindcss";
@config "./path/to/tailwind.config.js";
```
A few notes:
- Both CommonJS and ESM config files are supported (loaded directly via
`import()` in Node)
- This is not yet supported in Intellisense or Prettier — should
hopefully land next week
- TypeScript is **not yet** supported in the config file — this will be
handled in a future PR.
---------
Co-authored-by: Philipp Spiess <[email protected]>
Co-authored-by: Adam Wathan <[email protected]>
Co-authored-by: Robin Malfait <[email protected]>
