title: setInterval() will not run immediately
body: <p>I want to define a object that hold a interval that can be reset</p>
  
  <pre><code>var intervalHolder = {
      make : function() {
          this.clean();
          this.interval = setInterval(function () {
              console.log("make interval");
          }, 3.0 * 1000);
      },
      clean: function(){
          if(this.interval){
              console.log("clean interval");
              clearInterval(this.interval);
          }
      }
  };
  </code></pre>
  
  <p><code>intervalHolder.make()</code> was designed to clean old interval and make a new one</p>
  
  <p>but I found that when invoke the <code>intervalHolder.make()</code> multiple times , there will be a time gap between log <code>clean interval</code> and <code>make interval</code>, not immediately as expected. is clearInterval()' too time consuming?</p>