jsxstyle-loader is a webpack loader that extracts static style props from jsxstyle components into a separate CSS file.
Don’t know what jsxstyle is? Check out the jsxstyle README for more information.
Add a new rule object for
jsxstyle-loaderto your webpack config, below any other JS loaders.
jsxstyle-loaderrelies on untranspiled JSX to be present in order to extract styles. Since webpack loaders run from right to left and bottom to top,
jsxstyle-loadershould be placed at the end of your list of JS loaders.
jsxstyle-loader’s companion plugin to the
pluginssection of your webpack config.
Ensure your webpack config contains a loader that handles
When you’re done, the relevant parts of your webpack config should look like this:
const JsxstyleLoaderPlugin = ;moduleexports =// ...plugins:// ...module:rules:// ...test: /\.js$/use:// any loaders that transpile JSX should go above jsxstyle-loaderloader: 'your-cool-js-loader'// jsxstyle-loader goes at the endloader: 'jsxstyle-loader'test: /\.css$/use: 'your-cool-css-loader'// ...;
jsxstyle-loader will extract all static style props on a jsxstyle component into one class. This can lead to CSS classes that contain a lot of common style declarations. A good CSS minifier should help with this, but if you want a bit more control over how styles are grouped into CSS classes, you can provide an array of CSS style objects. When
jsxstyle-loader encounters a component that contains all styles in a style object, those styles will be extracted into a separate class name.
For example, with the following loader config:
loader: 'jsxstyle-loader'options:styleGroups:display: 'block'marginLeft: 15marginRight: 15
...and a jsxstyle component that looks like this:
import Block from 'jsxstyle';<Block ="blue" = = = />;
...the styles on this component will be extracted into three separate classes:
styleGroups parameter, all five style props would be extracted into one class.
namedStyleGroups config option is just like the
styleGroups config option, with one key difference: it is expected to be an object of CSS style objects, not an array. The key of the CSS style object will be used as the class name if all props and values are present on a jsxstyle component.
whitelistedModules config option allows you to add modules to the evaluation context. For example, with the following loader config, any prop on a jsxstyle component that references a value from
./LayoutConstants.js will be assumed to be evaluatable:
Note: the modules you specify as
whitelistedModuleswill not be transpiled, so make sure they’re in a format that’s compatible with your version of node.
jsxstyle-loader is preconfigured with most of
babylon’s plugins enabled, but if you need to enable additional plugins, you can specify an array of plugins with the
You can see a list of all available plugins in the
Out of the box,
jsxstyle-loader will use a non-deterministic class naming scheme. Because webpack’s module iteration order is not guaranteed, class names will differ slightly between builds of the same code. If you need class names to remain the same each time the same code is bundled, set the
classNameFormat option to
hash in your loader config. Class names will be generated using a content-based hash.
// look ma, no jsxstyle import<block ="red">This text will be red</block>
Instead of importing components from
jsxstyle/preact, don’t import anything and just use the dash-case version of the component name as if it’s a valid DOM element. When
jsxstyle-loader encounters one of these dash-case elements, it’ll treat it like the PascalCased equivalent component imported from
To enable this feature, set
liteMode in your loader options to either
Can I use
jsxstyle-loader with Flow?
Yes! Flow parsing is automatically enabled for any non-Typescript files.
Can I use
jsxstyle-loader with Typescript?
compilerOptionssection of your
ts-loader. Webpack loaders run from bottom to top, to
jsxstyle-loaderneeds to be placed before
ts-loaderin your webpack config.
- Add a loader that transpiles JSX, since
ts-loaderis now set to preserve JSX.
It’s not working 😩
Make sure the loader object
testregex matches JS files that use jsxstyle.
jsxstyle-loaderrelies on JSX still being around, so make sure it runs before
babel-loaderdoes its thing.
jsxstyle-loaderonly supports destructured
importsyntax:// Cool!import Block from 'jsxstyle';<Block />;// Neat!const Block = ;<Block />;// Nope :(const Block = Block;<Block />;
What are “static style props”?
Simply put, static style props are props whose values can be evaluated at build time. By default, this consists of any literal type (
null) as well as any variables provided to the evaluation context. The evaluation context is derived from the prop’s current scope.
For example, the
fontSize prop in the following component will be marked as evaluatable and will be extracted as
import Block from 'jsxstyle';const bestNumber = 42;<Block =>hello</Block>;
Any modules marked as whitelisted with the
whitelistedModules config option will also be added to the evaluation context.
If the value of a style prop is a ternary and both sides can be evaluated, the prop will be extracted and the ternary condition will be moved to the
If the value of a prop is a simple logical expression with the
&& operator, it will be converted to a ternary with a null alternate.
Inline styles… are bad.
See the jsxstyle FAQs.
Does it work with hot reloading?
It sure does, but using it in development will only cause confusion, since what you will see in the developer tools is the transformed JS.
jsxstyle-loader is a production optimisation.
One big one: CSS class names are not de-duplicated across components. Any CSS minifier that combines identical class names will handle deduplication.