TypeScript Development & Migration
Make a change in one package understandable to the next.
A green build is less reassuring when every difficult value becomes any. We improve how an existing JavaScript or TypeScript codebase describes data, exposes interfaces and detects incompatible changes, without turning a type cleanup into an unplanned rewrite.
DIRECT ANSWER
Wavect implements TypeScript adoption and contract improvements across existing applications, libraries and packages. We agree which boundaries become checked, how external data is validated and what remains outside the migration.
Best for
- Teams gradually adopting TypeScript in a JavaScript product
- Repositories whose shared types no longer describe the values moving between packages
Consider another approach
- A new product whose user journeys and architecture are still undecided
- A single frontend feature with no wider type or package problem
Start where a change breaks another part of the product
Useful starting points include a shared SDK, a mixed JavaScript/TypeScript package or inconsistent API response types. We inspect compiler settings, build tooling, dependency types and the current release process. A framework feature belongs with React or NestJS; this engagement owns the type and package boundaries that span those implementations.
A declared type does not validate an incoming response
We separate external values from trusted internal representations. Requests, stored records and third-party responses need explicit parsing or validation where they enter the application. Inside the boundary, discriminated states, null handling and clear error results help callers make the intended decisions. We remove misleading assertions where practical and record the exceptions that remain. A shared interface alone does not prove runtime compatibility.
Increase checking in a sequence the team can maintain
The migration plan identifies a small package or workflow, its consumers and the conditions for accepting the change. JavaScript and TypeScript can coexist while we improve coverage. We agree compiler settings, public exports and build checks before widening the scope. The TypeScript migration guide provides the language reference; your dependencies and delivery constraints determine the sequence. Broad architecture replacement remains Legacy Modernization.
An SDK update that exposes a changed response
Illustrative acceptance scenario: a quote API introduces a new result state. An exhaustive consumer check identifies the unhandled branch during the build, while an unfamiliar external response fails runtime validation with a useful diagnostic. Existing supported responses still pass their tests. We agree which consumers participate and how versions roll out. This describes proposed acceptance, not an achieved client result or a promise that types catch every defect.
Leave rules that another contributor can follow
The handover contains the changed packages, checks, remaining type gaps and an example of extending a public contract. Owners can see where assertions or generated types are still necessary. We review whether the next developer can add a case without weakening the checks. Bring the repository, a reproducible build and sanitized examples of the data that currently causes confusion.
Questions before you start
No. We can start with one package or boundary and keep existing JavaScript in the same delivery plan. The scope records the coverage gained and the parts intentionally left unchanged.
No. Static checking does not establish what a network response contains or whether a business rule is correct. Runtime validation and behavior tests remain part of the agreed boundary.
Yes. Compiler settings, exported contracts and package responsibilities can be improved within the current stack. A framework migration needs a separate decision.
No. The relevant contracts may live in one repository or several packages. We choose versioning and consumer checks around how your team actually releases software.
Review your TypeScript boundaries
Tell us where a change becomes difficult to trust: a package, SDK, API response or JavaScript migration. Include the current build setup and the consumers that must keep working.