Day 1 of 60
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Static analysis & type-time
Linting & formatting
Most fights in code review aren't about correctness, they're about style. A linter is the cheapest way to make those fights extinct.
ProblemStyle drift, common bug patterns, and review bikeshedding.
How it works
Configurable static analyzers that check for known anti-patterns and enforce style. Auto-fix where possible. Run pre-commit and in CI.
Try it
A self-contained mini-lab. Click through to see the technique catch a real bug.
Click Run ESLint to scan the file.
What it catches
Anti-patterns (loose equality, unused promises, dead code, missing await). Eliminates entire classes of style argument from review.
Tools
ESLint · OSS ruff · OSS golangci-lint · OSS clippy · OSS
Verdict by project size
Small
Must
Medium
Must
Large
Must
Extra-large
Must
Cost
| Project size | Setup | Maint / mo | Tool / mo | CI / run |
|---|---|---|---|---|
| Small <10k LOC | 2h | 0.5h | $0 | +0.5m |
| Medium 10–100k LOC | 1d | 2h | $0 | +1m |
| Large 100k–1M LOC | 3d | 8h | $0 | +2m |
| Extra-large >1M LOC | 8d | 30h | $0 | +5m |
Setup = engineer-days to first useful run ·
Maint = engineer-hours / month at steady state ·
Tool = out-of-pocket $ / month ·
CI = minutes added (or saved) per pipeline run
Lifecycle & ownership
When in lifecycle
Code Build
Pre-commit / IDE · Runs locally before code leaves the developer's machine.
Who owns it
Developer
Authoring + the inner loop
Collaborates with: Security / AppSec
Reference implementations
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ESLint core repository
Production-grade lint rule engine, fixtures, and rule-test patterns.
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typescript-eslint monorepo
Typed linting rules, fixtures, and parser integration for TypeScript projects.
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Ruff repository
Fast Python linting and formatting implementation with a broad rule suite.
Quick check
What is linting *least* effective at finding?
One question. Pick the best answer. Your streak is saved locally on this device.
Save the lesson
Download SVG ↓
Screenshot for a 1:1, drop it in Slack, or download the SVG.