title: Length of array in Typescript - access members
body: <p>I have a declared type</p>
  <pre><code>type Vehiculo={
    [key: string]: string;
  };
  
  let allCars:Vehiculo = {Ford: &quot;Ka&quot;, GM:&quot;Sonic&quot;, Audi:&quot;A4&quot;};
  </code></pre>
  <p>How can I get the length of this array?</p>
  <p>Definitely, allCars.length is not right</p>