use: Javascript / jQuery
// similar behavior as an HTTP redirect
window.location.replace("http://www.stackoverflow.com");
// similar behavior as clicking on a link
window.location.href = "http://stackoverflow.com";
Or .htaccess:
RewriteEngine On
RewriteBase /
Rewritecond %{HTTP_HOST} ^www\.yoursite\.com$ [NC]
RewriteRule ^(.*)$ https://yoursite.com/$1 [R=301,L]
and The PHP method:
$protocol = (@$_SERVER["HTTPS"]    == "on") ? "https://" : "http://";
if (substr($_SERVER['HTTP_HOST'], 0, 4) !== 'www.') {
    header('Location: '.$protocol.'www.'.$_SERVER    ['HTTP_HOST'].'/'.$_SERVER['REQUEST_URI']);
    exit;
}
Ajax
$.ajax({
    type: "POST",
    url: reqUrl,
    data: reqBody,
    dataType: "json",
    success: function(data, textStatus) {
        if (data.redirect) {
            // data.redirect contains the string URL to redirect to
            window.location.href = data.redirect;
        }
        else {
            // data.form contains the HTML for the replacement form
            $("#myform").replaceWith(data.form);
        }
    }
});