Lesson 1 / 27

Introduction to Code Quality Tools

Learn how ESLint finds bugs and enforces rules while Prettier formats code, and why teams use both together.

The essential idea

ESLint and Prettier are complementary tools: ESLint catches errors and enforces code quality, while Prettier handles formatting. Together they ensure consistency and catch bugs early.

See the workflow

ESLint checks for errors, Prettier formats code. They work together in your development pipeline.

ESLint and Prettier workflow diagram. — Figure 1.1 — The complete quality workflow.

Why this matters

Consistent code prevents merge conflicts, improves readability, and catches bugs automatically. Teams using ESLint and Prettier spend less time in code review.

Quick check

Quick check: What is the main difference between ESLint and Prettier?

They do the same thing.
ESLint catches errors; Prettier formats code.
Prettier catches errors; ESLint formats code.
They are the same tool

Answer

ESLint catches errors; Prettier formats code. — ESLint is a linter (quality checker), Prettier is a code formatter. They complement each other.