TypeScript 6.0 --noEmit: separating type-checking from transpilation in CI pipelines

Short summary

TypeScript 6.0's --noEmit flag lets teams use tsc purely for type-checking while bundlers like esbuild or swc handle transpilation in parallel, cutting build times 60-80%. The article explains how to configure tsconfig for type-only builds, why application code should never call tsc for output, and the one exception: library authors still need tsc to emit .d.ts declaration files.

• •--noEmit makes tsc a pure type-checker, enabling parallel builds with faster transpilers like esbuild/swc
• •Modern bundlers strip TypeScript syntax 10-20x faster than tsc transpiles but cannot validate types
• •Library authors still need tsc to emit .d.ts files, but application code should never emit via tsc

Generated with AI, which can make mistakes.