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    typescript-strictifier

    by Markus Isaksson

    Migrate JS to TS and upgrade existing TypeScript to strict mode with intelligent type inference and refactoring.

    Updated May 2026
    Security scanned
    One-time purchase

    $12

    One-time purchase

    ⚡ Also available via Agensi MCP — your AI agent can load this skill on demand via MCP. Learn more →

    Included in download

    • Convert legacy JavaScript modules to production-ready TypeScript code.
    • Scan for and replace unsafe 'any' types with precise interfaces and generics.
    • network automation included
    • Includes example output and usage patterns
    • Instant install

    See it in action

    Finding #1 — Load-bearing any
    Severity: Critical
    Location: api/users.ts:12
    Fix:
    - export function save(user: any) {
    + export interface User { id: string; name: string }
    + export function save(user: User) {
        return db.put(user.id, user);
    }

    About This Skill

    Eliminate Technical Debt with Strict Type Safety

    Modernizing a JavaScript or TypeScript codebase is a daunting task. Manually fixing thousands of implicit any errors, removing @ts-ignore tags, and enabling strictNullChecks can take weeks of engineering time. The TypeScript Strictifier automates this process by intelligently inferring types and refactoring your code for maximum safety without changing runtime behavior.

    What it does

    • JS to TS Migration: Converts JavaScript files to TypeScript, inferring shapes from usage patterns.
    • Eliminate `any`: Replaces any, Object, and Function with narrow interfaces, literal types, or generics.
    • Fix Suppressions: Safely removes @ts-ignore and @ts-nocheck by resolving the underlying type mismatch.
    • Strict Null Handling: Replaces unsafe non-null assertions (!) with proper narrowing and optional chaining.
    • Generic Refactoring: Transforms broad union types into reusable generics to preserve type information across function boundaries.

    Why use this skill?

    Unlike generic AI prompts that might introduce runtime bugs or suggest "hallucinated" types, this skill follows a strict incremental migration strategy. It prioritizes load-bearing types that propagate unsafety through your call graph, providing a severity-scaled report of every change. The output includes targeted diffs and recommended tsconfig updates, making it an essential tool for library authors and teams maintaining enterprise-scale codebases.

    📖 Learn more: Best Code Review Skills for Claude Code →

    Use Cases

    • Convert legacy JavaScript modules to production-ready TypeScript code.
    • Enable strictNullChecks and resolve all resulting compiler errors safely.
    • Scan for and replace unsafe 'any' types with precise interfaces and generics.
    • Generate minimal .d.ts declarations for untyped third-party dependencies.

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    $12

    One-time