title: How is TypeScript 100.0% written in TypeScript?
body: <p>In <a href="https://github.com/Microsoft/TypeScript" rel="noreferrer">TypeScript repository on GitHub</a> and according to GitHub, the repository just included 100.0% TypeScript <em>(.ts files)</em> </p>
  
  <p><a href="https://i.stack.imgur.com/Is7XE.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Is7XE.png" alt="enter image description here"></a></p>
  
  <p>How does it work? and how TypeScript can compile itself to JavaScript just by itself?</p>