Lesson 1.1:
ESM & Engineering Flow

ESM by Default

In 2026, the JavaScript ecosystem has fully migrated to ES Modules (ESM). This lesson covers the advanced resolution logic and performance benefits of ESM in Node.js v26.

Module Resolution 2.0

Node.js now prioritizes exports in package.json for precise subpath routing, enabling cleaner imports and better tree-shaking.

// package.json
{
  "name": "resilient-service",
  "type": "module",
  "exports": {
    ".": "./src/index.js",
    "./utils": "./src/utils/core.js"
  }
}

The "type: module" Workflow

By declaring your project as an ES Module, you unlock native top-level await and seamless integration with modern tooling like Vite and Vitest.

The Senior Engineering Flow

A senior engineer's workflow is defined by Atomic Commits and Clean History. Use interactive rebasing to maintain a narrative in your Git logs.

# Scenario: Squashing 3 messy commits into 1 feature commit
$ git rebase -i HEAD~3

# In the editor:
pick f7f3f6d Add logic
fixup d4d5f6e fix typo
fixup a1b2c3d rename var

Check Your Knowledge

Which command is used to find the exact commit that introduced a bug?

• git bisect
• git rebase