📝 TypeScript Playground

TypeScript Playground is an online TypeScript compiler and transpiler for small code snippets. Paste TypeScript, choose an ECMAScript target and module format, then inspect the JavaScript output, type annotations, and diagnostics without setting up a local tsconfig.json. TypeScript is a typed layer on top of JavaScript; the TypeScript Handbook describes it as static type checking for JavaScript programs before they run.

Common uses:

• Test a TypeScript interface, generic function, enum, union type, or async example before adding it to a project.
• Compare output for targets such as ES5, ES2017, and ESNext.
• See how module choices such as CommonJS, AMD, UMD, System, and ES6 affect generated JavaScript.
• Check strict-mode behavior, especially missing parameter types with noImplicitAny.
• Share a minimal reproduction for a TypeScript learning question, code review, or documentation example.

Compiler options:

• Target controls the JavaScript language level emitted for the runtime you support; the official compiler options reference documents supported targets.
• Module controls import and export output. TypeScript follows the JavaScript module model described in the TypeScript modules guide.
• Strict mode enables stricter checks so nullability, function types, implicit any, and related edge cases are easier to catch during development.
• No implicit any flags parameters where TypeScript cannot infer a type and would otherwise fall back to any.

Example: function greet(name: string): string { return `Hello, ${name}`; } compiles to JavaScript with the type annotations removed. An interface such as interface User { id: number; email?: string; } is compile-time structure only, so it disappears from emitted JavaScript after type checking.

Limitations: this playground is best for isolated snippets. It does not replace a full project build with the official tsc compiler, npm package resolution, framework-specific transforms, declaration generation, bundling, linting, or runtime validation. TypeScript types are erased from emitted JavaScript, so API payloads and user input still need runtime checks. JavaScript language behavior is standardized by ECMA-262, while TypeScript configuration details such as target, module, strict, and noImplicitAny are maintained in the TSConfig reference.