title: Prevent double tap zoom without jQuery
body: <p>In latest iOS Safari, unexpected double tap zoom cannot prevent, so my full-screen map application sometimes lost control of users.</p>
  
  <p>I found the solution with jQuery, it works well.</p>
  
  <pre><code>$.fn.nodoubletapzoom = function() {
      $(this).bind('touchstart', function preventZoom(e) {
          var t2 = e.timeStamp;
          var t1 = $(this).data('lastTouch') || t2;
          var dt = t2 - t1;
          var fingers = e.originalEvent.touches.length;
          $(this).data('lastTouch', t2);
          if (!dt || dt &gt; 500 || fingers &gt; 1) {
              return; // not double-tap
          }
          e.preventDefault(); // double tap - prevent the zoom
          // also synthesize click events we just swallowed up
          $(e.target).trigger('click');
      });
  };
  $('body').nodoubletapzoom();
  </code></pre>
  
  <p>But I want to do this without jQuery.</p>
  
  <p>What is the equivalent to this code without jQuery?</p>