A Script that shows me one screen or another depending on the device that visits it

To find out if it's a smartphone with javascript (taken from this answer ):

var isMobile = false; //initiate as false
// device detection
if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|ipad|iris|kindle|Android|Silk|lge |maemo|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(navigator.userAgent) 
    || /1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(navigator.userAgent.substr(0,4))) isMobile = true;

And to redirect:

// como si fuera un redirect HTTP -- Esta es la más probable que necesitas
window.location.replace("http://es.stackoverflow.com");

// como si se hiciera un click a un link
window.location.href = "http://es.stackoverflow.com";

Alternatively you can check (instead of looking if it is a mobile) the widthtotal of the screen with screen.widthwhich it returns the maximum width of the client's screen.

I have this script in php I don't know if you can use it or it has to be in javascript. Here's the code just in case:

    /**************************SCRIPT VALIDAR SI ES UN MOVIL, TABLET...****************************************/

$tablet_browser = 0;
$mobile_browser = 0;
$body_class = 'desktop';

if (preg_match('/(tablet|ipad|playbook)|(android(?!.*(mobi|opera mini)))/i', strtolower($_SERVER['HTTP_USER_AGENT'])))
{
    $tablet_browser++;
    $body_class = "tablet";
}

if (preg_match('/(up.browser|up.link|mmp|symbian|smartphone|midp|wap|phone|android|iemobile)/i', strtolower($_SERVER['HTTP_USER_AGENT']))) {
    $mobile_browser++;
    $body_class = "mobile";
}

if ((strpos(strtolower($_SERVER['HTTP_ACCEPT']),'application/vnd.wap.xhtml+xml') > 0) or ((isset($_SERVER['HTTP_X_WAP_PROFILE']) or isset($_SERVER['HTTP_PROFILE']))))
{
    $mobile_browser++;
    $body_class = "mobile";
}

$mobile_ua = strtolower(substr($_SERVER['HTTP_USER_AGENT'], 0, 4));
$mobile_agents = array(
    'w3c ','acs-','alav','alca','amoi','audi','avan','benq','bird','blac',
    'blaz','brew','cell','cldc','cmd-','dang','doco','eric','hipt','inno',
    'ipaq','java','jigs','kddi','keji','leno','lg-c','lg-d','lg-g','lge-',
    'maui','maxo','midp','mits','mmef','mobi','mot-','moto','mwbp','nec-',
    'newt','noki','palm','pana','pant','phil','play','port','prox',
    'qwap','sage','sams','sany','sch-','sec-','send','seri','sgh-','shar',
    'sie-','siem','smal','smar','sony','sph-','symb','t-mo','teli','tim-',
    'tosh','tsm-','upg1','upsi','vk-v','voda','wap-','wapa','wapi','wapp',
    'wapr','webc','winw','winw','xda ','xda-');

if (in_array($mobile_ua,$mobile_agents))
{
    $mobile_browser++;
}

if (strpos(strtolower($_SERVER['HTTP_USER_AGENT']),'opera mini') > 0)
{
    $mobile_browser++;
    //Check for tablets on opera mini alternative headers
    $stock_ua = strtolower(isset($_SERVER['HTTP_X_OPERAMINI_PHONE_UA'])?$_SERVER['HTTP_X_OPERAMINI_PHONE_UA']:(isset($_SERVER['HTTP_DEVICE_STOCK_UA'])?$_SERVER['HTTP_DEVICE_STOCK_UA']:''));
    if (preg_match('/(tablet|ipad|playbook)|(android(?!.*mobile))/i', $stock_ua))
    {
      $tablet_browser++;
  }
}


/*************************************FIN SCRIPT***************************************/

EDITION

if ($tablet_browser > 0)
{
    include('nombre_del_archivo_para_tablet.html');
}
else if($mobile_browser > 0)
{
    include('nombre_del_archivo_para_movil.html');
}
else
{
    include('nombre_del_archivo_para_pc.html');
}

Hope this can help you

What I was actually looking for was something like this: This detects the width of the device that visits it and then redirects the user to one website or another.

<script type="text/javascript">
  <!--
  if (screen.width <= 800) {
    window.location = "http://m.domain.com";
  }
  //-->
</script>

To me he...

<script type="text/javascript">
<!--
if (screen.width <= 800) {
window.location = "http://m.domain.com";
}
//-->
</script>

It has stopped working for me; now i work

<script type="text/JavaScript">
var dispositivo = navigator.userAgent.toLowerCase();
if( dispositivo.search(/iphone|ipod|ipad|android/) > -1 ){
document.location = "https://www.midominio.com/celular.html"; }
</script>

And it works perfectly, plus m.domain.com seems to be a subdomain probably created for cell phones with access through httaccess.

On my website I mainly use html and css; php only for hit counters and forms.