JavaScript vs TypeScript for MVPs: Why We Ship Without Types

We've shipped 10+ MVPs in JavaScript, not TypeScript. Before you close this tab in disgust, hear me out - this isn't about laziness or ignorance. We cut our teeth on Java 1.4 and strongly typed languages. We understand type safety. We've made an informed choice to skip it for MVPs, and we have the data to back it up.

Why This Debate Matters for MVPs

The TypeScript vs JavaScript debate usually devolves into ideology. TypeScript advocates point to compile-time safety. JavaScript defenders cite development speed. Both sides talk past each other because they're optimizing for different outcomes.

For MVPs specifically, the calculus is different. You're not building software that needs to last 10 years with 50 engineers maintaining it. You're validating whether anyone wants what you're building. Speed to market matters more than long-term maintainability - because 90% of MVPs won't have a long term.

According to CB Insights, 42% of startups fail because there's no market need. Spending an extra week on type safety while your competitor captures the market is optimizing the wrong thing.

Our Safety Net: 90%+ Test Coverage

Here's the thing - we don't skip TypeScript and cross our fingers. We skip TypeScript because we have something better for catching bugs in MVPs: comprehensive test coverage.

Real numbers from our published projects:

• New education platform: 2,000+ E2E tests covering every user interaction
• Internal tools: 90-99% coverage as a standard
• Across all demos: Thousands of assertions that run before every deploy

This isn't optional. Test coverage is a release gate. No green tests, no deploy. We've been doing this long enough that it's not a philosophy anymore - it's just how we work.

What does 90%+ coverage actually feel like? Last week we renamed 10 Vue components across a codebase. In a project without tests, that's a terrifying refactor - you're never quite sure what you broke. With 135 tests passing, we shipped with confidence. The tests told us exactly what worked and what didn't.

We also use TDD for complex logic. Recently, writing tests first revealed a routing bug that would have been a nightmare to debug in production. The test failed before we even ran the app. That's the kind of safety net that lets us move fast without breaking things.

What Tests Catch That Types Don't

TypeScript catches a specific class of errors: variable type mismatches, wrong argument types, undefined is not a function. These are real bugs, and catching them at compile time is genuinely useful.

But here's what TypeScript doesn't catch:

• Wrong business logic - Your tax calculation is incorrect, but the types are perfect
• Edge cases - What happens when the array is empty? When the user submits twice?
• Integration bugs - The API returns a different shape than you expected
• Race conditions - Two async operations complete in the wrong order
• User flow errors - The form submits but the data doesn't save

Tests catch all of the above. They also catch type errors - if you pass a string where a number is expected, your test fails when the function produces garbage output.

Think about it this way:

• TypeScript says: "this variable is a string"
• Tests say: "this function returns the correct business result for these 15 edge cases"

One is a subset of the other. If you have strong tests, types become redundant for the errors that matter most in an MVP.

The real trap is TypeScript with weak tests. You get compile-time confidence that your types are correct, but runtime surprises when your business logic is wrong. JavaScript with strong tests gives you confidence where it counts - in actual behavior.

The Speed Tax of TypeScript

For a 2-4 week MVP, TypeScript adds roughly 15-20% overhead. That's not a made-up number - it's what we've observed across projects where we've used both approaches.

Where does the time go?

Type definitions for everything. Every function, every object, every prop. For code that might get thrown away next month if the MVP doesn't validate, this is speculative investment.

Fighting @types/* packages. Third-party type definitions are often outdated, incomplete, or just wrong. You'll spend an hour debugging why the types don't match the actual library behavior, only to discover the type definitions haven't been updated in 18 months.

tsconfig.json complexity. Strict mode? Module resolution? Path aliases? These decisions take time, and the "wrong" choice creates friction throughout the project.

The any escape hatch. When types get complex, developers reach for any. Every any in your codebase defeats the purpose of TypeScript. If you're using any to get around type complexity, you've paid the TypeScript tax without getting the benefits.

Build step debugging. Source maps, compilation errors that don't match runtime behavior, slower feedback loops. These add friction to the rapid iteration that MVPs require.

The math is simple. A 4-week MVP becomes a 5-week MVP with TypeScript overhead. If 90% of MVPs die before needing that type safety, you've spent an extra week on something that provided no value.

Modern JavaScript Is Better Than You Remember

JavaScript in 2025 is not the JavaScript of 2015. The gap between typed and untyped JavaScript has narrowed significantly.

What we have now:

• Optional chaining (?.) - No more obj && obj.prop && obj.prop.value
• Nullish coalescing (??) - Sane defaults without falsy gotchas
• Destructuring - Clean extraction of values from objects and arrays
• Async/await - Readable asynchronous code without callback hell
• Classes and modules - Proper encapsulation and organization
• JSDoc comments - Full IntelliSense in VSCode without compilation

That last one is underrated. You can write JSDoc type annotations that give you autocomplete, parameter hints, and type checking in your editor - without a build step. It's not as powerful as TypeScript's type system, but it covers 80% of the value for 20% of the complexity.

A disciplined JavaScript engineer with comprehensive tests, JSDoc for public APIs, ESLint, Prettier, and consistent patterns can deliver maintainable code. We've done it across 10+ MVPs.

When TypeScript Is the Right Choice

We're not TypeScript haters. There are clear situations where TypeScript is the right choice:

Large teams (10+ engineers). When you can't fit everyone in a room, types become documentation. They communicate intent across team boundaries without requiring verbal coordination.

Long-lived codebases (5+ years). When many maintainers will touch the code over time, types help new developers understand existing code. The investment pays off over years.

Critical systems. Payments, healthcare, anything with legal liability. The extra safety is worth the extra time when bugs have severe consequences.

Complex data transformations. When you're reshaping data across many files, the compiler catches refactoring errors that tests might miss.

Junior-heavy teams. Types guide correct usage and catch mistakes before code review. They're training wheels that prevent common errors.

For MVPs built by small teams of experienced engineers who write comprehensive tests? TypeScript is overhead without proportional value.

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Want to build your MVP fast with a team that ships? Get in touch - we'd love to hear what you're building.