常用正则表达式：

        中文字符：/[\u4e00-\u9fa5]/;

        用户名：/[A-Za-z0-9_\-\u4e00-\u9fa5]+/;

        手机（国内）：/0?(13|14|15|18)[0-9]{9}/;

        手机（国外）：/[0-9-()（）]{7,18}/;

        腾讯QQ：/[1-9]([0-9]{5,11})/;

        Email地址：/\w[-\w.+]*@([A-Za-z0-9][-A-Za-z0-9]+\.)+[A-Za-z]{2,14}/;

        网址URL：/^((https|http|ftp|rtsp|mms)?:\/\/)[^\s]+/;

        身份证：/\d{17}[\d|x]|\d{15}/;

        邮政编码：/\d{6}/;

        IP地址：/(25[0-5]|2[0-4]\d|[0-1]\d{2}|[1-9]?\d)\.(25[0-5]|2[0-4]\d|[0-1]\d{2}|[1-9]?\d)\.(25[0-5]|2[0-4]\d|[0-1]\d{2}|[1-9]?\d)\.(25[0-5]|2[0-4]\d|[0-1]\d{2}|[1-9]?\d)/;

        格式日期：/\d{4}(\-|\/|.)\d{1,2}\1\d{1,2}/;

        匹配整数：/-?[1-9]\d*/;

        正整数：/[1-9]\d*/;

        负整数：/-[1-9]\d*/;

        正浮点数：/[1-9]\d*.\d*|0.\d*[1-9]\d*/;

        负浮点数：/-([1-9]\d*.\d*|0.\d*[1-9]\d*)/;

        双字节字符：/[^\x00-\xff]/;

        空白行：/\s/

用法如下：

       JS:
                var pattern = /[\u4e00-\u9fa5]/,
                str = '';
                console.log(pattern.test(str));

       PHP:
                $str = '';
                $isMatched = preg_match('/[\u4e00-\u9fa5]/', $str, $matches);
                var_dump($isMatched, $matches);