<script type="text/javascript">
  <!--
  var a=50,b="xxx";
  var arr="{id:"+a+",name:'"+b+"'}";
  //-->
</script>

<script type="text/javascript">
  <!--
  var a=50,b="xxx";
  var arr="{id:"+a+",name:'"+b+"'}";
  arr=eval('('+arr+')')
  alert(arr.name);
  //-->
</script>