title: Check if an object (or just a class) has a property
body: <p>Lets say I have a class:</p>
  
  <pre><code>module MyModule {
      export class MyClass {
         x:number;
         y:number;
      }
  }
  </code></pre>
  
  <p>Then I have a string, "x". How can I check if MyClass has property "x"?</p>
  
  <p>If I create an instance of MyClass and then do:</p>
  
  <pre><code>myClassInstance.hasOwnProperty("x");
  </code></pre>
  
  <p>it returns false unless x has a default value set. But I don't want to set default values for each property. It would be best if I even could do this without creating instance of MyClass.</p>