判断移动端并跳转到m域名的代码

<script>
    function is_mobile() {
            var regex_match = /(nokia|iphone|android|motorola|^mot-|softbank|foma|docomo|kddi|up.browser|up.link|htc|dopod|blazer|netfront|helio|hosin|huawei|novarra|CoolPad|webos|techfaith|palmsource|blackberry|alcatel|amoi|ktouch|nexian|samsung|^sam-|s[cg]h|^lge|ericsson|philips|sagem|wellcom|bunjalloo|maui|symbian|smartphone|midp|wap|phone|windows ce|iemobile|^spice|^bird|^zte-|longcos|pantech|gionee|^sie-|portalmmm|jigs browser|hiptop|^benq|haier|^lct|operas*mobi|opera*mini|320x320|240x320|176x220)/i;
            var u = navigator.userAgent;
            if (null == u) {
                return true;
            }
            var result = regex_match.exec(u);
            if (null == result) {
                return false
            } else {
                return true
            }
        }
        if (is_mobile()) {
            var pathname = window.location.pathname;
            var url = window.location.search; //获取url中"?"符后的字串
            window.location.href= '{m端域名}' + pathname + url;
        }
  </script>