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docs: update logic (#1587)
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@alexander-akait
alexander-akait authored Apr 8, 2024
1 parent 9c165a4 commit 15f793d
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214 changes: 84 additions & 130 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -337,7 +337,7 @@ type modules =
imports: object[];
exports: object[];
replacements: object[];
}) => any;
}) => Promise<void> | void;
};
```

Expand Down Expand Up @@ -1411,7 +1411,7 @@ type getJSON = ({
imports: object[];
exports: object[];
replacements: object[];
}) => any;
}) => Promise<void> | void;
```

Default: `undefined`
Expand Down Expand Up @@ -1457,81 +1457,21 @@ Enables a callback to output the CSS modules mapping JSON. The callback is invok
}
```

**webpack.config.js**

```js
// supports a synchronous callback
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
loader: "css-loader",
options: {
modules: {
getJSON: ({ resourcePath, exports }) => {
// synchronously write a .json mapping file in the same directory as the resource
const exportsJson = exports.reduce(
(acc, { name, value }) => ({ ...acc, [name]: value }),
{},
);

const outputPath = path.resolve(
path.dirname(resourcePath),
`${path.basename(resourcePath)}.json`,
);

const fs = require("fs");
fs.writeFileSync(outputPath, JSON.stringify(json));
},
},
},
},
],
},
};

// supports an asynchronous callback
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
loader: "css-loader",
options: {
modules: {
getJSON: async ({ resourcePath, exports }) => {
const exportsJson = exports.reduce(
(acc, { name, value }) => ({ ...acc, [name]: value }),
{},
);

const outputPath = path.resolve(
path.dirname(resourcePath),
`${path.basename(resourcePath)}.json`,
);

const fsp = require("fs/promises");
await fsp.writeFile(outputPath, JSON.stringify(json));
},
},
},
},
],
},
};
```

Using `getJSON`, it's possible to output a files with all CSS module mappings.
In the following example, we use `getJSON` to cache canonical mappings and
add stand-ins for any composed values (through `composes`), and we use a custom plugin
to consolidate the values and output them to a file:

**webpack.config.js**

```js
const path = require("path");
const fs = require("fs");

const CSS_LOADER_REPLACEMENT_REGEX =
/(___CSS_LOADER_ICSS_IMPORT_\d+_REPLACEMENT_\d+___)/g;
const REPLACEMENT_REGEX = /___REPLACEMENT\[(.*?)\]\[(.*?)\]___/g;
const IDENTIFIER_REGEX = /\[(.*?)\]\[(.*?)\]/;
const REPLACEMENT_REGEX = /___REPLACEMENT\[(.*?)]\[(.*?)]___/g;
const IDENTIFIER_REGEX = /\[(.*?)]\[(.*?)]/;
const replacementsMap = {};
const canonicalValuesMap = {};
const allExportsJson = {};
Expand Down Expand Up @@ -1570,9 +1510,8 @@ function addReplacements(resourcePath, imports, exportsJson, replacements) {
// add them all to the replacements map to be replaced altogether later
replacementsMap[identifier] = classNames.replaceAll(
CSS_LOADER_REPLACEMENT_REGEX,
(_, replacementName) => {
return importReplacementsMap[resourcePath][replacementName];
},
(_, replacementName) =>
importReplacementsMap[resourcePath][replacementName],
);
} else {
// otherwise, no class names need replacements so we can add them to
Expand All @@ -1586,22 +1525,86 @@ function addReplacements(resourcePath, imports, exportsJson, replacements) {
}

function replaceReplacements(classNames) {
const adjustedClassNames = classNames.replaceAll(
return classNames.replaceAll(
REPLACEMENT_REGEX,
(_, resourcePath, localName) => {
const identifier = generateIdentifier(resourcePath, localName);

if (identifier in canonicalValuesMap) {
return canonicalValuesMap[identifier];
}

// recurse through other stand-in that may be imports
// Recurse through other stand-in that may be imports
const canonicalValue = replaceReplacements(replacementsMap[identifier]);

canonicalValuesMap[identifier] = canonicalValue;

return canonicalValue;
},
);
}

function getJSON({ resourcePath, imports, exports, replacements }) {
const exportsJson = exports.reduce((acc, { name, value }) => {
return { ...acc, [name]: value };
}, {});

if (replacements.length > 0) {
// replacements present --> add stand-in values for absolute paths and local names,
// which will be resolved to their canonical values in the plugin below
addReplacements(resourcePath, imports, exportsJson, replacements);
} else {
// no replacements present --> add to canonicalValuesMap verbatim
// since all values here are canonical/don't need resolution
for (const [key, value] of Object.entries(exportsJson)) {
const id = `[${resourcePath}][${key}]`;

canonicalValuesMap[id] = value;
}

return adjustedClassNames;
allExportsJson[resourcePath] = exportsJson;
}
}

class CssModulesJsonPlugin {
constructor(options) {
this.options = options;
}

// eslint-disable-next-line class-methods-use-this
apply(compiler) {
compiler.hooks.emit.tap("CssModulesJsonPlugin", () => {
for (const [identifier, classNames] of Object.entries(replacementsMap)) {
const adjustedClassNames = replaceReplacements(classNames);

replacementsMap[identifier] = adjustedClassNames;

const [, resourcePath, localName] = identifier.match(IDENTIFIER_REGEX);

allExportsJson[resourcePath] = allExportsJson[resourcePath] || {};
allExportsJson[resourcePath][localName] = adjustedClassNames;
}

fs.writeFileSync(
this.options.filepath,
JSON.stringify(
// Make path to be relative to `context` (your project root)
Object.fromEntries(
Object.entries(allExportsJson).map((key) => {
key[0] = path
.relative(compiler.context, key[0])
.replace(/\\/g, "/");

return key;
}),
),
null,
2,
),
"utf8",
);
});
}
}

module.exports = {
Expand All @@ -1610,63 +1613,14 @@ module.exports = {
{
test: /\.css$/i,
loader: "css-loader",
options: {
modules: {
getJSON: ({ resourcePath, imports, exports, replacements }) => {
const exportsJson = exports.reduce(
(acc, { name, value }) => ({ ...acc, [name]: value }),
{},
);

if (replacements.length > 0) {
// replacements present --> add stand-in values for absolute paths and local names,
// which will be resolved to their canonical values in the plugin below
addReplacements(
resourcePath,
imports,
exportsJson,
replacements,
);
} else {
// no replacements present --> add to canonicalValuesMap verbatim
// since all values here are canonical/don't need resolution
for (const [key, value] of Object.entries(exportsJson)) {
const id = `[${resourcePath}][${key}]`;

canonicalValuesMap[id] = value;
}

allExportsJson[resourcePath] = exportsJson;
}
},
},
},
options: { modules: { getJSON } },
},
],
},
plugins: [
{
apply(compiler) {
compiler.hooks.done.tap("CssModulesJsonPlugin", () => {
for (const [identifier, classNames] of Object.entries(
replacementsMap,
)) {
const adjustedClassNames = replaceReplacements(classNames);
replacementsMap[identifier] = adjustedClassNames;
const [, resourcePath, localName] =
identifier.match(IDENTIFIER_REGEX);
allExportsJson[resourcePath] = allExportsJson[resourcePath] || {};
allExportsJson[resourcePath][localName] = adjustedClassNames;
}

fs.writeFileSync(
"./output.css.json",
JSON.stringify(allExportsJson, null, 2),
"utf8",
);
});
},
},
new CssModulesJsonPlugin({
filepath: path.resolve(__dirname, "./output.css.json"),
}),
],
};
```
Expand All @@ -1675,11 +1629,11 @@ In the above, all import aliases are replaced with `___REPLACEMENT[<resourcePath

```json
{
"/foo/bar/baz.module.css": {
"foo/bar/baz.module.css": {
"main": "D2Oy",
"header": "thNN"
},
"/foot/bear/bath.module.css": {
"foot/bear/bath.module.css": {
"logo": "sqiR",
"info": "XMyI"
}
Expand Down
1 change: 1 addition & 0 deletions src/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -274,6 +274,7 @@ export default async function loader(content, map, meta) {
);

const { getJSON } = options.modules;

if (typeof getJSON === "function") {
try {
await getJSON({ resourcePath, imports, exports, replacements });
Expand Down
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