NarrowType

Replace unsafe TypeScript type assertions with proper type guards and narrowing

Code & DevelopmentPaid

NarrowType scans TypeScript codebases to find type assertions, any-typed variables, and broad union types that could be replaced with discriminated unions and type guard functions. The tool generates specific replacement code using proper control flow narrowing, branded types, and exhaustive switch patterns. Teams migrating large JavaScript codebases to TypeScript use it to progressively tighten types while code review teams use it to enforce no-assertion policies in critical paths.

Key Features

• ✓Assertion detection
• ✓Guard generation
• ✓Branded types
• ✓Exhaustive patterns
• ✓Migration assistance