php - make bootstrap alert disappear automatically -

i have form whch sends data databse, after data sent want show success msg, dont want stay rather disappear after short while.

$nameerr=$drug_iderr=$priceerr=$quantityerr=$dateerr=$dateinvalid="";  $drug_id=$name=$price=$quantity=$date="";  if(isset($_post['submit'])){  $drug_id=mysql_real_escape_string(addslashes($_post['drug_id'])); $name=mysql_real_escape_string(addslashes($_post['name'])); $price=mysql_real_escape_string(addslashes($_post['price'])); $quantity=mysql_real_escape_string(addslashes($_post['quantity'])); $date=mysql_real_escape_string(addslashes($_post['date']));       if(empty($drug_id)){         $drug_iderr="required";          }     elseif(empty($name)){         $nameerr="required";          }     elseif(empty($price)){         $priceerr="required";         }      elseif(empty($quantity)){         $quantityerr="required";         }      elseif(empty($date)){         $dateerr="required";         }     elseif(!preg_match('/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/', $date)){          $dateinvalid="invalid date format";         }     else{          //send data database here         $_session['success']="drug added successfully";         $drug_id=$name=$price=$quantity=$date="";           }  } 

the following form

<div class="well">       <form id="register-form" class="form-horizontal" method="post" action="<?php echo $_server['php_self']; ?>">         <legend>add new drug</legend>         <?php  if(!empty($_session['success'])){           echo '<div class="alert alert-success">'.$_session['success'].'</div>'; unset($_session['success']);} ?>           <div class="control-group">             <label class="control-label">id</label>             <div class="controls">                 <div class="input-prepend">                 <span class="add-on"><i class="icon-ban-circle"></i></span>                     <input type="text" class="input-xlarge" id="drug_id" name="drug_id" placeholder="drug id"                      value="<?php echo htmlspecialchars($drug_id); ?>">                 </div>                  <span class="error"><?php echo $drug_iderr;?></span>             </div>          </div>         <div class="control-group ">             <label class="control-label">name</label>             <div class="controls">                 <div class="input-prepend">                 <span class="add-on"><i class="icon-pills"></i></span>                     <input type="text" class="input-xlarge" id="name" name="name" placeholder="drug name"                     value="<?php echo htmlspecialchars($name)?>">                  </div>                <span class="error"><?php echo $nameerr;?></span>             </div>         </div>         <div class="control-group">             <label class="control-label">price</label>             <div class="controls">                 <div class="input-prepend">                 <span class="add-on"><i class="icon-dollars"></i></span>                     <input type="text" class="input-small" id="price" name="price" placeholder="drug price"                     value="<?php echo htmlspecialchars($price); ?>">                 </div>                  <span class="error"><?php echo $priceerr; ?></span>             </div>         </div>           <div class="control-group">             <label class="control-label">quantity</label>             <div class="controls">                 <div class="input-prepend">                 <span class="add-on"><i class="icon-ban-circle"></i></span>                     <input type="text" id="quantity" class="input-mini" name="quantity" placeholder="quantity"                     value="<?php echo htmlspecialchars($quantity);?>">                 </div>                  <span class="error"><?php echo $quantityerr;?></span>             </div>         </div>           <div class="control-group">             <label class="control-label">expire date</label>             <div class="controls">             <div class="input-prepend">             <span class="add-on"><i class="icon-time"></i></span>             <td><input type="text" name="date"  id="date"   class="span2" placeholder="expire date"             value="<?php echo htmlspecialchars($date); ?>"/>             </div>               <span class="error"><?php  echo  $dateerr.$dateinvalid; ?></span>      </div>        </div>           <div class="control-group">         <label class="control-label"></label>           <div class="controls">             <button type="submit" class="btn btn-success" name="submit" >add</button>            </div>      </div>        </form>     </div> 

now can show alert don knw how make disappear

try this:

$('.alert').hide() 

or use fading:

$('.alert').fadeout(300)