Cross Side Validation script in PHP

    function crosssidescriptvalidation($keyvalue){
                    global $mosConfig_live_site;

    
                        
                        $keyvalue=strip_tags($keyvalue);
                        $keyvalue=utf8_decode($keyvalue);
                        $keyvalue=htmlspecialchars($keyvalue);
                        $keyvalue = str_replace("\"", "", $keyvalue);
                        $keyvalue = str_replace(">", "", $keyvalue);
                        $keyvalue = str_replace("\<", "", $keyvalue);
                        $keyvalue = str_replace(";:( )", "", $keyvalue);
                        $rediredtUrl=$mosConfig_live_site;                       
                        if(stristr($keyvalue,"<script>")){
                        
                         header("location:$rediredtUrl");
                        }
                        return $keyvalue;
    
    }