TypeScript Playground
LiveWrite TypeScript and see compiled JavaScript output in real-time.
Understanding TypeScript
TypeScript extends JavaScript with a static type system that catches errors at compile time — type mismatches, missing properties, incorrect function arguments, and null reference risks. The TypeScript compiler (tsc) transforms TypeScript into JavaScript, stripping type annotations and applying syntax downleveling for target environments. Understanding what JavaScript code TypeScript produces is essential for performance analysis, debugging runtime behavior, and learning how TypeScript features (enums, decorators, namespace merging) translate to runtime JavaScript.
A browser-based TypeScript playground that compiles your TypeScript code to JavaScript in real-time. See how interfaces, generics, enums, type guards, and decorators translate to JavaScript. Configure compiler options like target, module system, and strict mode. No installation needed.
The Devkitr TypeScript Playground compiles TypeScript to JavaScript in your browser, showing the compiled output alongside type checker diagnostics. Write TypeScript with interfaces, generics, enums, conditional types, and other features to see the generated JavaScript and any type errors — without installing the TypeScript compiler or configuring a project.
In a typical development workflow, TypeScript Playground becomes valuable whenever you need to write typescript and see compiled javascript output in real-time. Whether you are working on a personal side project, maintaining production applications for a company, or collaborating with a distributed team across time zones, having a reliable browser-based inspection tool eliminates the need to install desktop software, write one-off scripts, or send data to third-party services that may log or retain your information. Since TypeScript Playground processes everything locally on your device, your data stays private and your workflow stays uninterrupted — open a browser tab, paste your input, get your result.
Key Features
Real-Time Compilation
TypeScript compiles as you type, showing the JavaScript output and any type errors instantly without manual build steps.
Configurable Compiler Options
Adjust target (ES5, ES2020, ESNext), module system (CommonJS, ESM), strictness settings, and other tsconfig options to match your project.
Type Error Diagnostics
Displays TypeScript compiler errors with error codes, detailed messages, and squiggly underlines at the exact location of type violations.
JavaScript Output View
Shows the generated JavaScript side-by-side with the TypeScript source, revealing how type-only constructs are compiled away.
How to Use TypeScript Playground
Write TypeScript Code
Enter TypeScript in the editor — use interfaces, type annotations, generics, enums, and other TypeScript features.
Configure Compiler Settings
Set the target JavaScript version, module system, and strictness options to match how your project compiles TypeScript.
Check Type Errors
Review any type checking errors displayed below the editor — each error shows the location, code, and a detailed diagnostic message.
Inspect the Output
Examine the compiled JavaScript to understand how TypeScript constructs translate to runtime code and what the JavaScript engine actually executes.
Use Cases
Experimenting with TypeScript Features
Try new TypeScript features like satisfies, const type parameters, or decorator metadata to understand their behavior before using them in projects.
Understanding Enum Compilation
See how TypeScript enums compile to JavaScript objects or inline constants, informing your decision between enums, union types, and const assertions.
Debugging Type-Level Logic
Test conditional types, mapped types, and template literal types to verify they produce the expected type resolutions for different input types.
Sharing Interactive Code Examples
Create TypeScript examples with specific compiler settings for bug reports, Stack Overflow answers, or team discussions.
Pro Tips
Enable strict mode in the playground to match most production TypeScript configurations and catch maximum type errors.
Compare ES5 vs ESNext output to see how TypeScript downlevels async/await, classes, and destructuring for older targets.
Use the playground to test type narrowing patterns — see how TypeScript infers types inside conditional branches, typeof guards, and discriminated unions.
Check how declaration files (.d.ts) would look by enabling the declaration compiler option in the settings.
Common Pitfalls
Assuming TypeScript type annotations exist at runtime
Fix: Type annotations, interfaces, and type aliases are completely erased during compilation. Use runtime checks (typeof, instanceof) for runtime type safety.
Using the any type to silence all errors instead of fixing them
Fix: The any type disables type checking for that value, defeating TypeScript's purpose. Use unknown with type guards for values of truly unknown type.
Not realizing that TypeScript enums generate runtime JavaScript code
Fix: Unlike interfaces and types, enums produce JavaScript objects at runtime. Use const enum or union types if you want zero runtime overhead.
Frequently Asked Questions
QDoes it support the latest TypeScript features?
It supports core TypeScript features including interfaces, generics, enums, type guards, decorators, and utility types.
QCan I configure compiler options?
Yes. Set target (ES5, ES6, ESNext), module (CommonJS, ESM), and toggle strict mode.
QDoes it show type errors?
It performs basic type-stripping compilation. For full type-checking, use the official TypeScript playground.
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