How to Migrate Your CLI Tool from CommonJS to ESM

How to Migrate Your CLI Tool from CommonJS to ESM The JavaScript ecosystem is moving to ES Modules. Major packages like chalk , ora , and execa have dropped CommonJS support entirely — if you require() them, you get an error. For CLI tool authors, this means migrating to ESM or getting stuck on outdated dependency versions. This guide walks through the migration step by step, covering the non-obvious gotchas that trip up most developers. Why Migrate Now Three reasons ESM migration can't wait: Dependencies are ESM-only : chalk v5, ora v7, execa v8, and many others only support import Top-level await : ESM lets you use await at the top level — no more wrapping everything in async IIFEs Tree shaking : ESM enables better bundling and dead code elimination Step 1: Update package.json { "type" : "module" } This single line changes how Node.js interprets .js files in your project — from CommonJS to ESM. Every .js file now uses import / export instead of require / module.exports . Step 2: Conv