chore: add ESM type: module to package.json by JoshuaKGoldberg · Pull Request #109319 · getsentry/sentry

JoshuaKGoldberg · 2026-02-25T15:41:58Z

Switches the default module system for internal config/script files in this repo from CJS to ESM by specifying "type": "module" in the package.json file. In order to support that:

.mjs files are renamed to .js, since .js is now ESM instead of CJS
.js files using module.exports/require (CJS) are now using export/import (ESM)
Include globs in config files are updated to omit .mjs, as that extension is no longer necessary

Quick Node.js CJS/ESM primer

If you're new to the hullabaloo that is Node.js module loading: welcome! There are effectively two main ways that Node.js files are able to export & import things:

CommonJS ("CJS"): an old Node.js-specific syntax that's always been available in Node.js
- Exporting: module.exports.key = value;
- Importing: const { key } = require("./file");
ECMAScript Modules ("ESM"): a new JavaScript standard that's only become widely supported in the last few years
- Exporting: export const key = value;
- Importing: import { key } from "./file.js";

Any one file is able to use only one syntax. For legacy reasons Node.js defaults to interpreting .js files as CJS. Node.js can be told to change that (switch to ESM) in two ways:

Broad: in a package.json, setting "type": "module switches the default to ESM
Per-file: using an explicit .cjs or .mjs extension for a file switches the file to CJS or ESM, respectively

ESM is generally/mostly considered to be a better syntax for a bunch of technical points. Because it's more explicit & less dynamic, it works better for a lot of tools.

Fixes https://linear.app/getsentry/issue/ENG-6928/add-esm-type-module-to-packagejson

.github/workflows/scripts/deploy.js

tests/js/jest-pegjs-transform.js

JoshuaKGoldberg · 2026-02-25T15:44:22Z

tsconfig.json

  "include": [
-    "*.config.mjs",
+    "*.config.js",
    "*.config.ts",


[Question] Could we just go with *.config.* or *.config.*s? Was the having two includes with explicit extensions intentional?

🤷 *.config.* seems fine, just less explicit

natemoo-re

I'm impressed with how little this seems to break so far! Looking good.

.github/workflows/scripts/deploy.js

package.json

natemoo-re · 2026-02-25T16:47:40Z

tsconfig.json

  "include": [
-    "*.config.mjs",
+    "*.config.js",
    "*.config.ts",


🤷 *.config.* seems fine, just less explicit

JoshuaKGoldberg · 2026-02-25T17:14:30Z

~~Test failures will be resolved by #109326.~~ ✅

github-actions · 2026-02-26T17:24:10Z

🚨 Warning: This pull request contains Frontend and Backend changes!

It's discouraged to make changes to Sentry's Frontend and Backend in a single pull request. The Frontend and Backend are not atomically deployed. If the changes are interdependent of each other, they must be separated into two pull requests and be made forward or backwards compatible, such that the Backend or Frontend can be safely deployed independently.

Have questions? Please ask in the #discuss-dev-infra channel.

.github/workflows/scripts/deploy.js

scttcper

surprised jest doesn't explode

natemoo-re

We should have done this much sooner! Nice work 🎉

.github/workflows/scripts/deploy.js

cursor · 2026-02-27T13:15:54Z

scripts/test.js

@@ -1,4 +1,4 @@
-'use strict';
+import {run} from 'jest';


ESM import hoisting defeats env var initialization order

Low Severity

The static import {run} from 'jest' on line 1 is hoisted and evaluated before the process.env assignments on lines 5–7. In the original CJS version, require('jest') was called at the end of the file (after all env setup), matching the comment "Do this as the first thing so that any code reading it knows the right env." Now the jest module (and its transitive dependencies) loads before NODE_ENV, TZ, etc. are set, and the unhandledRejection handler is also registered after the import. A dynamic await import('jest') or moving the env setup to a separate preloaded module would preserve the original execution order.

I don't think this matters? Jest always runs in test mode, and PUBLIC_URL & TZ are Sentry - only constructs that I know of.

evanpurkhiser

this is dope

Replace hand-rolled findJsonFiles with Node's built-in fs.promises.glob, and convert CJS require/module.exports to ESM import/export to align with the repo-wide ESM migration in #109319. Co-Authored-By: Claude <noreply@anthropic.com>

eslint.config.js

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

tests/js/test-balancer/index.js

.github/workflows/scripts/getsentry-dispatch.js

.github/workflows/scripts/deploy.js

Directly changes files from `.mjs` to ~`.mts`. I would have preferred the cleaner `.ts` but that will require adding `"type": "module"` to `package.json`, which is more work (which would be a great followup!).~ `.ts`, building on #109319's switching the package to be ESM by default. Imports are now TypeScript-style extension-less ones. Now that the plugin's files are typed, this applies a few types cleanups: * Uses [typescript-eslint's `RuleCreator`](https://typescript-eslint.io/developers/custom-rules#rulecreator) to create rules, which gives nicer typings than the built-in ESLint `Rule` * Updates node types from [`estree`](https://github.com/estree/estree) (only vanilla JS types) to [`@typescript-eslint/estree`](https://typescript-eslint.io/packages/typescript-estree) (full TS node types) * Converts JSDoc types to full TypeScript syntax This PR should have no changes to the lint rules' behavior. The only runtime code changes are for deleting unused parameters.

linear · 2026-03-02T22:20:05Z

ENG-6928 Add ESM type: module to package.json

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chore: convert ESLint files from .js/.mjs to .ts #109310

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feat(ci): report backend test fails #109543

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chore: add ESM type: module to package.json

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