Fix TypeScript module resolution for direct filter imports

[Copilot]

This PR fixes a TypeScript module resolution issue that occurs when users upgrade to Style Dictionary v4 and switch to modern module resolution strategies (moduleResolution: "bundler", "node16", or "nodenext").

Problem

When importing filters directly, users encountered the following error:

import { isDuration } from 'style-dictionary-utils/dist/filter/isDuration.js'
import { isDimension } from 'style-dictionary-utils/dist/filter/isDimension.js'

Cannot find module 'style-dictionary-utils/dist/filter/isDuration.js' or its corresponding type declarations.ts(2307)

Root Cause

The package.json exports configuration was missing explicit type declarations for subpath exports:

"exports": {
  ".": "./dist/index.js",
  "./filter/*": "./dist/filter/*"
}

Modern TypeScript module resolution requires explicit declaration of both JavaScript files and their corresponding TypeScript declaration files.

Solution

Updated the exports configuration to properly specify both .js and .d.ts files:

"exports": {
  ".": {
    "import": "./dist/index.js",
    "types": "./dist/index.d.ts"
  },
  "./filter/*.js": {
    "import": "./dist/filter/*.js",
    "types": "./dist/filter/*.d.ts"
  },
  "./dist/filter/*.js": {
    "import": "./dist/filter/*.js",
    "types": "./dist/filter/*.d.ts"
  }
}

This fix supports both import patterns:

• Documented pattern: import { isDuration } from 'style-dictionary-utils/filter/isDuration.js'
• User pattern from issue: import { isDuration } from 'style-dictionary-utils/dist/filter/isDuration.js'

Verification

• ✅ All existing tests pass (131/131)
• ✅ TypeScript compilation works with bundler, node16, and nodenext module resolution
• ✅ Both main imports and direct filter imports work correctly
• ✅ Maintains full backward compatibility

This is a minimal change that only updates the package.json exports configuration without modifying any source code.

Fixes #95.

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.