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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 d={a:111};
console.log(d[d['a']++, 'a']);
</script>


<script id="jsbin-source-javascript" type="text/javascript"> var d={a:111};
console.log(d[d['a']++, 'a']);</script></body>
</html>