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TypeScript Best Practices
Opens with creditsA practical guide to writing TypeScript that catches real bugs without fighting you. It covers compiler settings for TypeScript 6 and 7, modeling data with types, avoiding unsafe escape hatches, validating data at runtime boundaries, generics, typed linting and organizing larger codebases, with short examples you can copy.
Written by Tauseef Fayyaz7 chapters, 33 practicesAbout 26 min25 quiz questionsReviewed 13 October 2026What you will learn
7 chapters · about 26 min
1Compiler settings and TypeScript 7The tsconfig decides how much TypeScript checks for you. This chapter covers the strict flags, module settings for your runtime and the move to the native TypeScript 7 compiler.6 practices · 6 min
- 1Keep strict on and add the checks strict leaves out
- 2Choose module and moduleResolution for the runtime that runs your code
- 3Set types and rootDir explicitly
- 4Write erasable TypeScript and mark type-only imports
- 5Move to TypeScript 7 by clearing the 6.0 deprecations first
- 6Run the type checker in CI, separate from the build
6 in this chapterOpen this chapter2Modeling data with typesGood types describe the states your data can really be in, and nothing else. This chapter covers unions, literal types, readonly data and where to write annotations.6 practices · 4 min
- 1Annotate function boundaries and let TypeScript infer the rest
- 2Model states as a discriminated union, not a bag of optional fields
- 3Make switches exhaustive with a never check
- 4Use literal unions and as const instead of loose strings and enums
- 5Mark data you do not mean to change as readonly
- 6Brand ids and units that share a primitive type
6 in this chapterOpen this chapter- Avoiding unsafe escape hatchesany, type assertions, non-null assertions and ignore comments switch off the checks you turned on. This chapter shows the safer tools for each case.5 practices · 4 minOpens with credits
- Validating data at runtime boundariesTypes are erased before your code runs. This chapter covers validating data where it enters the program, typing configuration and handling errors safely.4 practices · 3 minOpens with credits
- Generics and utility typesGenerics let one function or type work with many types while keeping them related. This chapter follows the handbook guidelines for simple, useful generics and built-in utility types.4 practices · 3 minOpens with credits
- Typed linting and async codeSome bugs type check fine but are still bugs, especially around promises. This chapter covers type-aware linting and safe async patterns.4 practices · 3 minOpens with credits
- Organizing larger codebases and librariesAs a codebase grows, build speed, boundaries and published types matter more. This chapter covers project references, library publishing and keeping dependencies healthy.4 practices · 3 minOpens with credits
About this guide
These TypeScript best practices are for developers who already write TypeScript and want their types to catch more bugs with less ceremony. Every practice is checked against the official TypeScript handbook, the TSConfig reference and the release posts for TypeScript 6.0 and TypeScript 7.0, so the settings and advice match the compiler you install today.
2026 changed the ground under TypeScript. TypeScript 6.0, released in March, turned on strict by default, changed several other defaults and deprecated old options such as target: es5, baseUrl and moduleResolution: node. TypeScript 7.0, released in July, is a native port of the compiler written in Go. The TypeScript team reports typical full builds 8 to 12 times faster than 6.0, and the options 6.0 deprecated are now hard errors. Node.js can also run .ts files directly by stripping types, which rewards a style of TypeScript that uses only erasable syntax.
The habits that make TypeScript worth it have not changed. Turn on the strict checks and a few more. Model your data so impossible states cannot be written. Prefer unknown and narrowing over any and as. Remember that types disappear at runtime, so validate everything that enters your program from the outside. Keep generics simple, and let a type-aware linter catch the mistakes the compiler allows.
Each chapter below is a set of instructions with a short reason, things to do and avoid, and a code example where it helps. Start with the first chapter: compiler settings decide how much the rest of your types can protect you.
Common questions
What is the latest version of TypeScript?
As of October 2026 the latest major release is TypeScript 7.0, announced on July 8, 2026. It is a native port of the compiler written in Go, with the same type checking as TypeScript 6.0 and much faster builds. TypeScript 6.0, released in March 2026, is the last version built on the JavaScript codebase and is still needed by tools that use the compiler API.
Is TypeScript 7 faster than TypeScript 6?
Yes. The TypeScript team reports typical full builds 8 to 12 times faster than 6.0, with lower peak memory on every project they measured. In the VS Code codebase, the time until the editor shows the first error fell from about 17.5 seconds to under 1.3 seconds.
Should I use strict mode in TypeScript?
Yes. Since TypeScript 6.0, strict is on by default. Add noUncheckedIndexedAccess, noImplicitOverride and exactOptionalPropertyTypes as well, since they catch real bugs and are not part of strict.
Should I use any or unknown in TypeScript?
Use unknown for values you have not checked yet, such as parsed JSON or caught errors. It forces you to narrow before use. any turns off type checking for the value and everything it flows into, so keep it out of application code.
Can Node.js run TypeScript directly?
Yes, for erasable syntax. Node.js strips types by default since v22.18.0 and v23.6.0, and the feature is stable from v24.12.0 and v25.2.0. It does not type check and does not support enums, namespaces with runtime code or parameter properties, so turn on erasableSyntaxOnly and run tsc --noEmit separately.
What is the difference between satisfies and as in TypeScript?
satisfies checks that a value matches a type and keeps the narrower inferred type, so missing or misspelled keys are reported. as tells the compiler to trust you and reports nothing if the value does not really match. Prefer satisfies for config objects and lookup tables.
Sources (8)
Checked against these, last on 13 October 2026.
- Announcing TypeScript 7.0, TypeScript blogdevblogs.microsoft.com/typescript/announcing-typescript-7-0/
- Announcing TypeScript 6.0, TypeScript blogdevblogs.microsoft.com/typescript/announcing-typescript-6-0/
- TSConfig Reference, TypeScript docswww.typescriptlang.org/tsconfig/
- Narrowing, TypeScript Handbookwww.typescriptlang.org/docs/handbook/2/narrowing.html
- More on Functions, TypeScript Handbookwww.typescriptlang.org/docs/handbook/2/functions.html
- TypeScript 4.9 release notes, TypeScript docswww.typescriptlang.org/docs/handbook/release-notes/typescript-4-9.html
- Modules: TypeScript, Node.js docsnodejs.org/api/typescript.html
- Linting with Type Information, typescript-eslinttypescript-eslint.io/getting-started/typed-linting/
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