fix: 🐛 watch mode

✅ Closes: #9

README.md

@@ -2,7 +2,8 @@
 [![TypeScript](https://img.shields.io/badge/%3C%2F%3E-TypeScript-%230074c1.svg)](http://www.typescriptlang.org/)
 [![code style: prettier](https://img.shields.io/badge/code_style-prettier-f8bc45.svg)](https://github.com/prettier/prettier)
 [![npm version](https://badge.fury.io/js/esbuild-plugin-less.svg)](https://www.npmjs.com/package/esbuild-plugin-less)
-[![David](https://img.shields.io/david/dev/iam-medvedev/esbuild-plugin-less)](https://david-dm.org/iam-medvedev/esbuild-plugin-less)
+[![David](https://status.david-dm.org/gh/iam-medvedev/esbuild-plugin-less.svg?type=dev)](https://david-dm.org/iam-medvedev/esbuild-plugin-less)
+[![David](https://status.david-dm.org/gh/iam-medvedev/esbuild-plugin-less.svg?type=peer)](https://david-dm.org/iam-medvedev/esbuild-plugin-less)
 [![Codecov](https://img.shields.io/codecov/c/github/iam-medvedev/esbuild-plugin-less)](https://codecov.io/gh/iam-medvedev/esbuild-plugin-less)
 [![FOSSA Status](https://app.fossa.com/api/projects/git%2Bgithub.com%2Fiam-medvedev%2Fesbuild-plugin-less.svg?type=shield)](https://app.fossa.com/projects/git%2Bgithub.com%2Fiam-medvedev%2Fesbuild-plugin-less?ref=badge_shield)
 [![semantic-release](https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg)](https://github.com/semantic-release/semantic-release)
@@ -19,6 +20,8 @@ yarn add esbuild-plugin-less -D
 
 ## Usage
 
+### Simple example
+
 You can see the example [here](./example).
 
 ```ts
@@ -36,6 +39,26 @@ build({
 });
 ```
 
+### Watch mode
+
+More information about watch mode [here](https://esbuild.github.io/api/#watch).
+
+```ts
+import { build } from 'esbuild';
+import { lessLoader } from 'esbuild-plugin-less';
+
+build({
+  watch: true, // enable watch mode
+  entryPoints: [path.resolve(__dirname, 'index.ts')],
+  bundle: true,
+  outdir: path.resolve(__dirname, 'output'),
+  plugins: [lessLoader()],
+  loader: {
+    '.ts': 'ts',
+  },
+});
+```
+
 ## Options
 
 `lessLoader` accepts all valid options from less.js. You can find a complete list of options [here](http://lesscss.org/usage/#less-options).

__tests__/less-utils.test.ts

@@ -0,0 +1,18 @@
+import path from 'path';
+import { getLessImports } from '../src/less-utils';
+
+describe('less-utils', () => {
+  it('get imports paths', () => {
+    const filePath = path.resolve(__dirname, '../example/styles/style.less');
+    const imports = getLessImports(filePath);
+
+    expect(imports).toEqual(
+      expect.arrayContaining([
+        expect.stringContaining('styles/style-2.less'),
+        expect.stringContaining('styles/inner/style-3.less'),
+        expect.stringContaining('styles/inner/style-4.css'),
+        expect.stringContaining('styles/inner/style-5.css'),
+      ]),
+    );
+  });
+});

example/build.ts

@@ -2,7 +2,21 @@ import * as path from 'path';
 import { build } from 'esbuild';
 import { lessLoader } from '../src/index';
 
+// isProduction flag for watch mode
+const isProduction = process.env.NODE_ENV === 'production';
+
 build({
+  watch: isProduction
+    ? false
+    : {
+        onRebuild(error) {
+          if (error) {
+            console.error('Build failed:', error);
+          } else {
+            console.error('Build succeeded');
+          }
+        },
+      },
   entryPoints: [path.resolve(__dirname, 'index.ts')],
   bundle: true,
   outdir: path.resolve(__dirname, 'output'),

package.json

@@ -16,7 +16,8 @@
   ],
   "scripts": {
     "build": "NODE_ENV=production ts-node ./scripts/build.ts",
-    "build:example": "ts-node ./example/build.ts",
+    "dev:example": "ts-node ./example/build.ts",
+    "build:example": "NODE_ENV=production ts-node ./example/build.ts",
     "commit": "yarn git-cz",
     "prepublish": "yarn test && yarn types && yarn build",
     "types": "NODE_ENV=production tsc --emitDeclarationOnly --declaration --outDir build",
@@ -40,7 +41,7 @@
     "@types/jest": "^26.0.20",
     "@types/node": "^14.14.22",
     "cz-conventional-changelog": "^3.3.0",
-    "esbuild": "^0.8.54",
+    "esbuild": "^0.11.2",
     "git-cz": "^4.7.6",
     "husky": "^5.1.3",
     "jest": "^26.6.3",
@@ -52,7 +53,7 @@
     "typescript": "^4.1.3"
   },
   "peerDependencies": {
-    "esbuild": "^0.8.x"
+    "esbuild": "^0.11.x"
   },
   "dependencies": {
     "@types/less": "^3.0.2",

src/index.ts

@@ -1,25 +1,26 @@
-import * as path from 'path';
+import path from 'path';
 import { promises as fs } from 'fs';
 import { Plugin } from 'esbuild';
 import less from 'less';
-
-const namespace = 'less';
+import { getLessImports } from './less-utils';
 
 /** Less-loader for esbuild */
 export function lessLoader(options: Less.Options = {}): Plugin {
   return {
     name: 'less-loader',
     setup: (build) => {
       // Resolve *.less files with namespace
-      build.onResolve({ filter: /\.less$/ }, (args) => {
+      build.onResolve({ filter: /\.less$/, namespace: 'file' }, (args) => {
+        const filePath = path.resolve(process.cwd(), path.relative(process.cwd(), args.resolveDir), args.path);
+
         return {
-          path: path.resolve(process.cwd(), path.relative(process.cwd(), args.resolveDir), args.path),
-          namespace,
+          path: filePath,
+          watchFiles: !!build.initialOptions.watch ? [filePath, ...getLessImports(filePath)] : undefined,
         };
       });
 
       // Build .less files
-      build.onLoad({ filter: /.*/, namespace }, async (args) => {
+      build.onLoad({ filter: /\.less$/, namespace: 'file' }, async (args) => {
         const content = await fs.readFile(args.path, 'utf-8');
         const dir = path.dirname(args.path);
         const filename = path.basename(args.path);

src/less-utils.ts

@@ -0,0 +1,37 @@
+import fs from 'fs';
+import path from 'path';
+
+const importRegex = /@import(?:\s+\((.*)\))?\s+['"](.*)['"]/;
+const globalImportRegex = /@import(?:\s+\((.*)\))?\s+['"](.*)['"]/g;
+const importCommentRegex = /(?:\/\*(?:[\s\S]*?)\*\/)|(\/\/(?:.*)$)/gm;
+
+const extWhitelist = ['.css', '.less'];
+
+/** Recursively get .less/.css imports from file */
+export const getLessImports = (filePath: string): string[] => {
+  try {
+    const dir = path.dirname(filePath);
+    const content = fs.readFileSync(filePath).toString('utf8');
+
+    const cleanContent = content.replace(importCommentRegex, '');
+    const match = cleanContent.match(globalImportRegex) || [];
+
+    const fileImports = match
+      .map((el) => {
+        const match = el.match(importRegex);
+        return match[2];
+      })
+      .filter((el) => !!el)
+      .map((el) => path.resolve(dir, el));
+
+    const recursiveImports = fileImports.reduce((result, el) => {
+      return [...result, ...getLessImports(el)];
+    }, fileImports);
+
+    const result = recursiveImports.filter((el) => extWhitelist.includes(path.extname(el).toLowerCase()));
+
+    return result;
+  } catch (e) {
+    return [];
+  }
+};

yarn.lock

@@ -2359,10 +2359,10 @@ es6-promisify@^5.0.0:
   dependencies:
     es6-promise "^4.0.3"
 
-esbuild@^0.8.54:
-  version "0.8.54"
-  resolved "https://registry.npmjs.org/esbuild/-/esbuild-0.8.54.tgz#2f32ff80e95c69a0f25b799d76a27c05e2857cdf"
-  integrity sha512-DJH38OiTgXJxFb/EhHrCrY8eGmtdkTtWymHpN9IYN9AF+4jykT0dQArr7wzFejpVbaB0TMIq2+vfNRWr3LXpvw==
+esbuild@^0.11.2:
+  version "0.11.2"
+  resolved "https://registry.npmjs.org/esbuild/-/esbuild-0.11.2.tgz#3b995e107f2054d9090402b98a3b79ceffd05eb6"
+  integrity sha512-8d5FCQrR+juXC2u9zjTQ3+IYiuFuaWyKYwmApFJLquTrYNbk36H/+MkRQeTuOJg7IjUchRX2Ulwo1zRYXZ1pUg==
 
 escalade@^3.1.1:
   version "3.1.1"