TypeScript Playground Guide

Use the TypeScript Playground to try a typed snippet without setting up a project.

An interface disappears at runtime

Clear the editor, open Code examples, and choose Typed function. It adds:

interface Rectangle {
  width: number;
  height: number;
}
function area(rectangle: Rectangle): number {
  return rectangle.width * rectangle.height;
}
console.log('Area:', area({ width: 6, height: 4 }));

Press Run. The first run downloads the compiler; later requests can use the browser’s normal HTTP cache. The output is Area: 24. The interface and annotations are removed before JavaScript executes: they describe types, not runtime validation.

For example, assigning a string to a variable annotated number is a semantic type error, but this runner may still execute it. Use a real TypeScript type checker when validating a project. The optional Monaco editor can show diagnostics, but those do not block Run.

Coding exercises and patterns

The examples include odd/even numbers, prime numbers up to 30, factorial, Fibonacci, FizzBuzz, palindrome, bubble sort, binary search, word frequency, OOP and six triangle/pyramid/diamond patterns. The shared JavaScript examples also work as TypeScript; Typed function and Generic function demonstrate TypeScript-specific syntax.

Choosing an example preserves your current code below it, pauses Auto-run, and shows an explanation of the expected result. Clear first if you want a single exercise. Star-pattern spaces are significant; the output uses monospace text and Copy output preserves those spaces and line breaks.

Input, limits and privacy

Use await prompt('Your name?', 'Ilham') for input and Send input to resume execution. This prompt returns a Promise, unlike window.prompt.

Each Run starts a fresh Worker. Stop interrupts even an infinite loop. Execution is limited to 30 seconds and 500 output rows. Timers can continue logging after the snippet returns until Stop, the next Run or the execution limit.

The tool does not save or upload your code or input. Compiler and optional editor assets are fetched from jsDelivr, which receives ordinary asset requests. Snippets can make network requests through browser APIs, so only run code you trust. A Worker is not a security sandbox.

Related playgrounds

• JavaScript Playground
• Python Playground
• Ruby Playground
• C Playground
• C++ Playground

Reference

• TypeScript compiler API: transpileModule