TypeScript Strict Mode Migration

15 items · Technical · Hard difficulty · 2 hours

Incrementally migrate to TypeScript strict mode, file-by-file.

• Create migration branch and back up tsconfig

  Open a new Git branch and save a copy of tsconfig.json to revert if needed.

• Run initial full type check (tsc --noEmit) and save error list

  Capture current compiler errors so you can measure progress during migration.

• Add //@ts-nocheck to files you will migrate later

  Temporarily silence type errors per file so you can focus on one file at a time.

• Enable noImplicitAny in tsconfig.json

  Turn on the flag under compilerOptions to detect implicit any usages.

• Fix implicit any errors by adding explicit types

  Add parameter and variable types or use 'unknown' before narrowing to specific types.

• Run tsc and adjust types iteratively after fixes

  Re-run the compiler frequently to catch dependent type errors as you change types.

• Enable strictNullChecks in tsconfig.json

  Enable to force explicit handling of null and undefined across the codebase.

• Audit nullable values and use optional chaining or checks

  Add null checks, defaults, or narrow types to safely handle nullable values.

• Enable strictPropertyInitialization in tsconfig.json

  Require class properties to be initialized or explicitly marked as definite.

• Initialize properties in constructors or use definite assignment (!) carefully

  Prefer initializing properties; use '!' only when you're certain the value will be set.

• Enable noImplicitReturns in tsconfig.json

  Detect functions that might exit without returning a value to avoid runtime bugs.

• Run incremental file migrations: remove //@ts-nocheck and fix each file

  Uncomment a single file, fix all type errors, run tsc, then remove the comment and commit.

• Add explicit return types to exported functions and public APIs

  Document intent and improve downstream type checking for consumers.

• Update lint and CI to enforce strict checks

  Enable typescript-eslint rules and run tsc --noEmit in CI to prevent regressions.

• Run full type check, remove temporary scaffolding, and merge branch

  Run tsc, run tests, remove remaining //@ts-nocheck comments, then merge when green.

Printed from TickYouOff — the interactive version tracks your progress and can be shared with others.