Build: Set Up TypeScript ESM Project with Path Aliases

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◆ Before you start

Prerequisites

TypeScript 5+Required
Node.js 18+ for ESM

📦

Step 1 of 1

Set Up TypeScript ESM Project with Path Aliases

Configure a TypeScript project with NodeNext module resolution and @/ path aliases.

Tasks

Initialize project with type: module

Set tsconfig moduleResolution: NodeNext

Add tsconfig-paths for runtime alias resolution

Create multi-entrypoint package.json exports

🎯 What You'll Learn

▸Use moduleResolution: NodeNext with .js extensions
▸Set up package.json exports map
▸Configure path aliases that work at runtime

Code

JSONpackage.json
1 {
2   "name": "my-lib",
3   "version": "1.0.0",
4   "type": "module",
5   "main": "./dist/index.js",
6   "exports": {
7     ".": {
8       "import": "./dist/index.js",
9       "types": "./dist/index.d.ts"
10     },
11     "./utils": {
12       "import": "./dist/utils.js",
13       "types": "./dist/utils.d.ts"
14     }
15   },
16   "scripts": {
17     "build": "tsc",
18     "dev": "node --loader ts-node/esm --require tsconfig-paths/register src/index.ts"
19   },
20   "devDependencies": {
21     "typescript": "^5.0.0",
22     "ts-node": "^10.9.0",
23     "tsconfig-paths": "^4.2.0"
24   }
25 }

💡 Pro Tips

▸Write ./utils.js even though the file is .ts — TypeScript finds the .ts automatically
▸tsconfig paths need a runtime companion (tsconfig-paths or bundler alias)

Expected Output

import from "./utils.js" resolves ts file; import from "@/lib" resolves to src/lib

Discussion

1 { 2 "name": "my-lib", 3 "version": "1.0.0", 4 "type": "module", 5 "main": "./dist/index.js", 6 "exports": { 7 ".": { 8 "import": "./dist/index.js", 9 "types": "./dist/index.d.ts" 10 }, 11 "./utils": { 12 "import": "./dist/utils.js", 13 "types": "./dist/utils.d.ts" 14 } 15 }, 16 "scripts": { 17 "build": "tsc", 18 "dev": "node --loader ts-node/esm --require tsconfig-paths/register src/index.ts" 19 }, 20 "devDependencies": { 21 "typescript": "^5.0.0", 22 "ts-node": "^10.9.0", 23 "tsconfig-paths": "^4.2.0" 24 } 25 }

1	{
2	"name": "my-lib",
3	"version": "1.0.0",
4	"type": "module",
5	"main": "./dist/index.js",
6	"exports": {
7	".": {
8	"import": "./dist/index.js",
9	"types": "./dist/index.d.ts"
10	},
11	"./utils": {
12	"import": "./dist/utils.js",
13	"types": "./dist/utils.d.ts"
14	}
15	},
16	"scripts": {
17	"build": "tsc",
18	"dev": "node --loader ts-node/esm --require tsconfig-paths/register src/index.ts"
19	},
20	"devDependencies": {
21	"typescript": "^5.0.0",
22	"ts-node": "^10.9.0",
23	"tsconfig-paths": "^4.2.0"
24	}
25	}