正则表达式验证日期

<script language="javascript"> function CheckDate(str){var Expression=/^((((1[6-9]|[2-9]\d)\d{2})(\/|\-)(0?[13578]|1[02])(\/|\-)(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})(\/|\-)(0?[13456789]|1[012])(\/|\-)(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})(\/|\-)0?2(\/|\-)(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$/; var objExp=new RegExp(Expression);if(objExp.test(str)==true){return true;}else{return false;}}function check(){var mydate = document.getElementById("mydate"); //获得日期文本框对象 if(mydate.value==""){//判断输入的日期是否为空alert("请输入日期！");mydate.focus();//使文本框获得焦点return;}if(!CheckDate(mydate.value)){//验证日期格式是否正确 alert("您输入的日期不正确，请注意日期格式！");mydate.focus();return;}document.getElementById("dateForm").submit();}</script>