title: Passing object with predefined props to class constructor es6
body: <p>I am trying to pass to my class constructor an object with predefined properties.</p>
  
  <p>like this </p>
  
  <pre><code>class Test {
  
  constructor({
      a = "test a",
      b = "test b"
      }) {
  
      }
  }
  </code></pre>
  
  <p>P.S. I know how to define properties of objects. I want to know how to predefine properties.</p>