title: ES6 class constructor shortcut for setting instance properties
body: <p>I seem to remember seeing a shortcut where you didn't have to do this.foo assignments in the constructor if the property and the constructor argument was named the same thing - but I can't seem to find the reference for it googling around.</p>
  
  <p>For example:</p>
  
  <pre><code>class Polygon {
    constructor(height, width) {
      this.height = height;
      this.width = width;
    }
  }
  </code></pre>
  
  <p>Could you instead do something like</p>
  
  <pre><code>class Polygon {
    constructor(height=height, width=width) { 
       // wasn't there a way to declare these arguments so it auto sets the instance variables?
    }
  }
  </code></pre>