【エラー対応】Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.

Next.js と Prisma でscript.ts を実行しようとした時に遭遇したエラーの解決記事

開発環境

$ sw_vers 
ProductName:            macOS
ProductVersion:         13.5.1
BuildVersion:           22G90

$ node -v
v19.2.0

$ npm -v
8.19.3

$ npx next -v
Next.js v13.4.19

$ npx prisma -v
prisma                  : 5.2.0

実行コード

script.ts

import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient()

async function main() {
  const dateWithUsers = await prisma.date.findMany({
    include: {
      users: true,
    },
  })
  console.log(JSON.stringify(dateWithUsers, null, 2))
  console.dir(dateWithUsers, { depth: null })
}

main()
  .then(async () => {
    await prisma.$disconnect()
  })
  .catch(async (e) => {
    console.log(e)
    await prisma.$disconnect()
    process.exit(1)
  })

エラー文

$ npx ts-node script.ts

(node:79287) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
/Users/xxx/git/maiamea/practice-next-prisma/script.ts:37
import { PrismaClient } from "@prisma/client";
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at internalCompileFunction (node:internal/vm:74:18)
    at wrapSafe (node:internal/modules/cjs/loader:1141:20)
    at Module._compile (node:internal/modules/cjs/loader:1182:27)
    at Module.m._compile (/Users/xxx/git/maiamea/practice-next-prisma/node_modules/ts-node/src/index.ts:1618:23)
    at Module._extensions..js (node:internal/modules/cjs/loader:1272:10)
    at Object.require.extensions.<computed> [as .ts] (/Users/xxx/git/maiamea/practice-next-prisma/node_modules/ts-node/src/index.ts:1621:12)
    at Module.load (node:internal/modules/cjs/loader:1081:32)
    at Function.Module._load (node:internal/modules/cjs/loader:922:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:82:12)
    at phase4 (/Users/xxx/git/maiamea/practice-next-prisma/node_modules/ts-node/src/bin.ts:649:14)

原因

tsconfig.json の設定の影響によるもの

解決策

• script.ts の拡張子を .mts に変更することで回避する
• ts-nodeの実行オプションに --esm をつける

npx ts-node --esm script.mts