JavaScript 使用 delete 删除数组元素的特性分析

<script type="text/javascript">
<!--
var days = ["Sunday","Monday","Tuesday","Wednesday",
  "Thursday","Friday","Saturday"];
document.write("Number of days:"+days.length);
  delete days[4];
document.write("<br />Number of days:"+days.length);
//-->
</script>

Number of days:7
Number of days:7