title: Babel: Function parameter types in ES6
body: <p>If I write the following piece of code and transpile it through <strong>Babel (6.5.0)</strong> it works correctly.</p>
  
  <pre><code>function foo (first: string, second: number) {
      // code here
  }
  </code></pre>
  
  <p><code>: string</code> and <code>: number</code> are just removed from the transpiled ES5 code.</p>
  
  <p>If I call the function using wrong parameter types, it does not result in any error/warning. They are informative even though do not have any functionality.</p>
  
  <p>I cannot find proper information about ES6's parameter typing on internet. Is parameter typing even part of ES6?</p>
  
  <p><strong>EDIT:</strong>
  This question got answered in the comments below and I wrapped the official answer based on them.</p>