--- title: Typescript. Runtime. And in Between. - Ariel Shulman -... description: TypeScript provides compile-time type safety but doesn't protect against runtime errors from external data sources like APIs. The TypeScript compiler works... canonical: https://daily.dev/posts/typescript-runtime-and-in-between---ariel-shulman---ndc-copenhagen-2025-hrdbcsoey twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Typescript. Runtime. And in Between. - Ariel Shulman - NDC Copenhagen 2025 | daily.dev og:description: TypeScript provides compile-time type safety but doesn't protect against runtime errors from external data sources like APIs. The TypeScript compiler works... og:url: https://daily.dev/posts/typescript-runtime-and-in-between---ariel-shulman---ndc-copenhagen-2025-hrdbcsoey og:image: https://api.daily.dev/og/posts/hRDbcsOeY.png og:image:alt: Typescript. Runtime. And in Between. - Ariel Shulman - NDC Copenhagen 2025 og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Typescript. Runtime. And in Between. - Ariel Shulman - NDC Copenhagen 2025 **[NDC Conferences](https://daily.dev/sources/ndc)** · 49 min read · 0 upvotes · 0 comments ## Summary TypeScript provides compile-time type safety but doesn't protect against runtime errors from external data sources like APIs. The TypeScript compiler works through four phases: parsing code into an Abstract Syntax Tree, binding references, type checking through tree traversal, and emitting JavaScript. Runtime validation libraries like Zod solve the gap between TypeScript's static types and runtime data by providing schema validation with automatic type inference. Advanced patterns like discriminated unions, nominal typing with symbols, and environment variable validation improve type safety. TypeScript is being rewritten in Go to achieve 10x performance improvements, addressing scalability issues in large codebases where JavaScript's limitations become apparent. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [TypeScript levels up with type stripping](https://daily.dev/posts/typescript-levels-up-with-type-stripping-gb9bktba8) · InfoWorld · 1 upvotes · 0 comments - [Zod \+ TypeScript: Schema Validation Made Easy – Frontend Masters Blog](https://daily.dev/posts/zod-typescript-schema-validation-made-easy-frontend-masters-blog-yv5epna6v) · Frontend Masters · 0 upvotes · 0 comments - [Zod: Type-Safe Schema Validation for TypeScript](https://daily.dev/posts/zod-type-safe-schema-validation-for-typescript-ea5i1fg8l) · Flavio Copes · 1 upvotes · 0 comments - [TypeScript Types as a Programming Language](https://daily.dev/posts/typescript-types-as-a-programming-language-dkrj7zn2j) · marmelab · 42 upvotes · 3 comments --- Tags: [#javascript](https://daily.dev/tags/javascript), [#nodejs](https://daily.dev/tags/nodejs), [#typescript](https://daily.dev/tags/typescript), [#zod](https://daily.dev/tags/zod) [View this post on daily.dev](https://daily.dev/posts/typescript-runtime-and-in-between---ariel-shulman---ndc-copenhagen-2025-hrdbcsoey) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Typescript. 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