js中比较时间字串大小

	var start = Date.parse($("#str_atBeginDate").val().replace("-","/"));
		var end = Date.parse($("#str_atTermDate").val().replace("-","/"));
<!--		var start = new Date($("#str_atBeginDate").val()).getTime();-->
<!--		var end = new Date($("#str_atTermDate").val()).getTime();-->
		if(start != NaN && end != NaN && start >= end){
			alert("签约到期时间不能小于合同生效时间  !");
		}