From f0d438f298bcb834f905181c5b2826ef4978cb7c Mon Sep 17 00:00:00 2001
From: Franco Zalamena <franco.zalamena@iterable.com>
Date: Tue, 7 Apr 2026 15:59:11 +0100
Subject: [PATCH] Add ESM package exports with conditional imports

Add tsconfig.esm.json for ES module builds and configure package.json
with conditional exports so that import resolves to ESM and require
continues to resolve to the existing CommonJS output.

Fixes #488

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 package.json      | 16 +++++++++++++---
 tsconfig.esm.json |  8 ++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)
 create mode 100644 tsconfig.esm.json

diff --git a/package.json b/package.json
index f67df8fd..d8dd73f4 100644
--- a/package.json
+++ b/package.json
@@ -20,8 +20,16 @@
     "typescript"
   ],
   "main": "./index.node.js",
+  "module": "./dist/esm/index.js",
   "browser": "./index.js",
   "types": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "import": "./dist/esm/index.js",
+      "require": "./dist/index.js",
+      "default": "./dist/index.js"
+    }
+  },
   "unpkg": "./index.js",
   "files": [
     "index.js",
@@ -29,7 +37,8 @@
     "index.node.js",
     "dist/*",
     "package.json",
-    "README.md"
+    "README.md",
+    "dist/esm/*"
   ],
   "dependencies": {
     "@pabra/sortby": "^1.0.1",
@@ -57,8 +66,9 @@
     "lint": "eslint src --ignore-pattern '*.test.*' --ignore-pattern '*.spec.*' --ext '.ts,.tsx'",
     "typecheck": "ttsc --noEmit true --emitDeclarationOnly false",
     "check-deps": "madge --extensions js,ts --circular dist",
-    "prepublishOnly": "yarn lint && yarn typecheck && yarn format && yarn build && yarn build:node",
-    "clean": "find . -name \"node_modules\" -exec rm -rf '{}' +"
+    "prepublishOnly": "yarn lint && yarn typecheck && yarn format && yarn build && yarn build:node && yarn build:esm",
+    "clean": "find . -name \"node_modules\" -exec rm -rf '{}' +",
+    "build:esm": "ttsc --project tsconfig.esm.json && babel src --out-dir ./dist/esm --extensions \".ts,.tsx\""
   },
   "devDependencies": {
     "@babel/cli": "^7.5.5",
diff --git a/tsconfig.esm.json b/tsconfig.esm.json
new file mode 100644
index 00000000..af361926
--- /dev/null
+++ b/tsconfig.esm.json
@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "module": "ESNext",
+    "outDir": "./dist/esm",
+    "declaration": false
+  }
+}