title: How to pass "this" to window setInterval
body: <p>Suppose I have a function a:  </p>
  
  <pre><code>function a() {
      this.b = 1;
      this.set = setInterval(function() {console.log(this.b);}, 200);
  }
  </code></pre>
  
  <p>So when a.set() is called the anonymous function will be called. But this won't work as this at that time when the function is triggered points to the window object. Also it's not a good idea to use a.b as there may be multiple instances of a.</p>
  
  <p>What is a good solution to this problem?</p>