下面代码执行结果为什么不一样呢？
<html>
<head>
</head>
<script type="text/javascript">
alert(/(\d{1,2}:\d{2})/.test("12:02"));
alert((new RegExp("(\d{1,2}:\d{2})")).test("2:00"));
alert((new RegExp("(\d{1,2}:\d{2})")).test("02:04"));
</script>
<body>
</body>
</html>
<html>
<head>
</head>
<script type="text/javascript">
alert(/(\d{1,2}:\d{2})/.test("12:02"));
alert((new RegExp("(\d{1,2}:\d{2})")).test("2:00"));
alert((new RegExp("(\d{1,2}:\d{2})")).test("02:04"));
</script>
<body>
</body>
</html>
<script type="text/javascript">
alert(/(\d{1,2}:\d{2})/.test("12:02"));
alert((new RegExp("\\d{1,2}:\\d{2}")).test("2:00"));
alert((new RegExp("\\d{1,2}:\\d{2}")).test("02:04"));
</script>用new RegExp的时候要注意转义