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<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>

<script id="jsbin-javascript">
var a = {
  counter: 0,
  b: {
    c: {
      d: function() {
        for (var i=0;i<5;i++) {
          setTimeout(function() {
            console.log(i, ++this.counter);
          }, 500);
        }
      }
    }
  }
};

a.b.c.d();
</script>


<script id="jsbin-source-javascript" type="text/javascript">var a = {
  counter: 0,
  b: {
    c: {
      d: function() {
        for (var i=0;i<5;i++) {
          setTimeout(function() {
            console.log(i, ++this.counter);
          }, 500);
        }
      }
    }
  }
};

a.b.c.d();
</script></body>
</html>