TypeScript Best Practices Review
In this page:
Core Concept
A best-practices review of a TypeScript codebase typically checks for any usage (each one is a gap in type safety), whether strict mode is enabled, and whether types are colocated sensibly rather than duplicated across files.
Example: Core Concept
// Checklist: grep for ": any", check strict mode, check for duplicated types.
function search(term: string): any { return term; } // flagged in a review
console.log(search("x"));Basic Setup
A basic review process runs tsc --noEmit with strict: true temporarily enabled (even if the project doesn't use it day-to-day) to surface how many latent type issues exist beneath the current configuration.
Example: Basic Setup
// tsc --noEmit --strict (run temporarily even if not the project default)
console.log("Reveals latent type issues hidden beneath the current config");Typed Example
A typed example of a common finding: a function typed to return SomeType | null where every actual call site immediately does result!.property (a non-null assertion) usually signals the type should just be narrowed properly instead of asserted away.
Example: Typed Example
interface Result { value: string; }
function find(id: number): Result | null {
return id === 1 ? { value: "found" } : null;
}
const result = find(2);
// result!.value is a red flag -- prefer narrowing instead:
if (result) console.log(result.value);Project Usage
In a real project, a periodic review also checks for overly broad types (object, Function, any[]) that technically compile but provide little real safety, replacing them with specific interfaces or generics.
Example: Project Usage
// Flag overly broad types found during review:
function process(data: object) { // too broad
console.log(data);
}
interface Payload { id: number; } // replace with something specific
process({ id: 1 } satisfies Payload);Best Practices
Track a metric like "count of any and @ts-ignore occurrences" over time in CI, since a rising trend usually means type debt is accumulating faster than it's being paid down.
Example: Best Practices
// CI metric: count of ": any" and "@ts-ignore" occurrences over time
let anyCount = 0;
let tsIgnoreCount = 0;
console.log("Track these counts in CI to catch rising type debt");Chapter Quiz — Complete all 14 topics to unlock
0/14 topics done
Complete these topics first:
- Todo App with TypeScript
- REST API with Express + TypeScript
- React Dashboard with TypeScript
- CLI Tool with TypeScript
- Library with TypeScript
- Full Stack TypeScript App
- TypeScript Design System
- TypeScript Monorepo Project
- Authentication System
- Real-time App with Socket.io
- GraphQL API with TypeScript
- Microservices with TypeScript
- TypeScript Best Practices Review
- What to Learn Next