From d7f6ddb38f9254b5e6a90629d40738dfc484badc Mon Sep 17 00:00:00 2001
From: Vlad Ivanov <vladivanov.dev@gmail.com>
Date: Mon, 24 Oct 2022 23:57:16 +0200
Subject: [PATCH] feat(loader): add functions support for locals

---
 src/loader.js | 18 +++++++++++-------
 src/utils.js  | 10 ++++++++++
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/src/loader.js b/src/loader.js
index 6de4e3d6..423a14f4 100644
--- a/src/loader.js
+++ b/src/loader.js
@@ -8,6 +8,7 @@ const {
   BASE_URI,
   SINGLE_DOT_PATH_SEGMENT,
   stringifyRequest,
+  stringifyLocal,
 } = require("./utils");
 const schema = require("./loader-options.json");
 
@@ -22,6 +23,7 @@ const MiniCssExtractPlugin = require("./index");
 /** @typedef {import("webpack").AssetInfo} AssetInfo */
 /** @typedef {import("webpack").NormalModule} NormalModule */
 /** @typedef {import("./index.js").LoaderOptions} LoaderOptions */
+/** @typedef {{ [key: string]: string | function } | function} Locals */
 
 /** @typedef {any} TODO */
 
@@ -38,7 +40,7 @@ const MiniCssExtractPlugin = require("./index");
 
 /**
  * @param {string} content
- * @param {{ loaderContext: import("webpack").LoaderContext<LoaderOptions>, options: LoaderOptions, locals: {[key: string]: string } | undefined }} context
+ * @param {{ loaderContext: import("webpack").LoaderContext<LoaderOptions>, options: LoaderOptions, locals: Locals | undefined }} context
  * @returns {string}
  */
 function hotLoader(content, context) {
@@ -95,7 +97,7 @@ function pitch(request) {
    * @returns {void}
    */
   const handleExports = (originalExports, compilation, assets, assetsInfo) => {
-    /** @type {{[key: string]: string } | undefined} */
+    /** @type {Locals | undefined} */
     let locals;
     let namedExport;
 
@@ -170,7 +172,8 @@ function pitch(request) {
               locals = {};
             }
 
-            locals[key] = originalExports[key];
+            /** @type {{ [key: string]: string }} */ (locals)[key] =
+              originalExports[key];
           }
         });
       } else {
@@ -228,15 +231,16 @@ function pitch(request) {
         ? Object.keys(locals)
             .map(
               (key) =>
-                `\nexport var ${key} = ${JSON.stringify(
-                  /** @type {{[key: string]: string }} */
-                  (locals)[key]
+                `\nexport var ${key} = ${stringifyLocal(
+                  /** @type {{ [key: string]: string | function }} */ (locals)[
+                    key
+                  ]
                 )};`
             )
             .join("")
         : `\n${
             esModule ? "export default" : "module.exports ="
-          } ${JSON.stringify(locals)};`
+          } ${stringifyLocal(/** @type {function} */ (locals))};`
       : esModule
       ? `\nexport {};`
       : "";
diff --git a/src/utils.js b/src/utils.js
index 416b38c1..68ab5f08 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -205,6 +205,15 @@ function getUndoPath(filename, outputPath, enforceRelative) {
     : append;
 }
 
+/**
+ *
+ * @param {string | function} value
+ * @returns {string}
+ */
+function stringifyLocal(value) {
+  return typeof value === "function" ? value.toString() : JSON.stringify(value);
+}
+
 module.exports = {
   trueFn,
   findModuleById,
@@ -216,5 +225,6 @@ module.exports = {
   BASE_URI,
   SINGLE_DOT_PATH_SEGMENT,
   stringifyRequest,
+  stringifyLocal,
   getUndoPath,
 };