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TypeScript

TypeScript adds static types to JavaScript to detect incompatibilities during development. In blockchain applications it describes contracts, APIs and states without replacing external data validation. It helps coordinate frontend, backend and SDK interfaces as functions and dependencies change; incoming API and RPC responses still require checks at runtime.

Written by Isaac GonzálezUpdated October 11, 2026

Key takeaways

  • TypeScript checks types before execution and compiles to JavaScript.
  • Types help keep contracts, APIs and interfaces aligned.
  • External data still requires validation at runtime.

What is TypeScript?

TypeScript adds a type system to JavaScript to describe data and detect incompatibilities during development. In a blockchain application it can represent addresses, contract responses, transaction states and network configurations. The resulting code usually runs as JavaScript in a browser or on a server.

Types establish a contract between parts of the codebase. When a function changes its parameters, incompatible calls can be detected before deployment. This is useful when the interface, backend and operational scripts evolve together and several teams depend on the same data structures.

How it works

The TypeScript checker analyses code and its configuration. Strict mode helps detect missing values and incorrect conversions. Types are removed when JavaScript is generated: an HTTP response, URL parameter or RPC result still needs runtime validation before it is trusted.

For EVM integrations, an ABI retaining literal type information lets compatible libraries infer function names and arguments. This inference describes the ABI included in the project; it does not automatically inspect the deployed contract. Network, address, ABI and implementation version must remain aligned through deployment and subsequent upgrades.

What TypeScript offers

A treasury application can share operation types across forms, APIs and reconciliation tasks. Instead of representing everything as generic strings, it distinguishes amounts in base units, network identifiers and pending, confirmed or failed states. This makes conversions and product decisions more explicit and easier to review.

On-chain amounts require integers and controlled decimal conversions. A bigint preserves precision but needs a serialization strategy when crossing a JSON API. The same discipline applies to a protocol SDK distributed to other teams: documentation and examples should preserve the meaning of each amount and identifier.

Limitations and selection criteria

TypeScript does not establish that an operation is economically valid or that a contract is secure. Type assertions and any can hide errors, while an outdated ABI still produces types consistent with incorrect information. Type checking complements integration tests and input validation rather than replacing them.

Adoption can proceed module by module, prioritising service boundaries and transaction signing flows. Continuous integration should run type checking explicitly because some tools transpile code without checking it. Its value should be assessed through detected errors and maintainability rather than universal claims about development speed.

Also known as

  • TS
  • TypeScript language
  • typed JavaScript
Development at Metlabs

How we approach a project with TypeScript

Development capabilities and use cases to assess how TypeScript fits your product.

What we build with TypeScript at Metlabs

  • Typed Web3 frontends

    Next.js + Wagmi + Viem with types generated from the ABI for autocompletion on functions and events.

  • SDKs and APIs

    Reusable client libraries with strict typing that ease third-party integration.

  • Node backends

    Indexers, webhooks and on-chain bots with end-to-end typing across contract, API and frontend.

  • Use case

    Contract-typed dApp

    A frontend deriving types from its configured ABI and checking deployment alignment.

  • Use case

    Custom indexer

    Node service that processes on-chain events and exposes them via a typed API consumed by the frontend.

Related content

Go deeper on TypeScript

Other Metlabs pages that expand on this entry.

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