我想要的效果是它在这个框里输出的时候始终看到的是最后输出的信息

php 输出到textarea 滚动条自动向下移动

<?php 
 class runtime 
 {  
     var $StartTime = 0;  
     var $StopTime = 0;  
   
     function get_microtime()  
     {  
         list($usec, $sec) = explode(' ', microtime());  
         return ((float)$usec + (float)$sec);  
     }  
   
     function start()  
     {  
         $this->StartTime = $this->get_microtime();  
     }  
   
     function stop()  
     {  
         $this->StopTime = $this->get_microtime();  
     }  
   
     function spent()  
     {  
         return round(($this->StopTime - $this->StartTime) * 1000, 1);  
     }  
   
 } 
   
   
  
 $runtime= new runtime; 
 
   

   echo '
   <textarea   rows= "5 "   cols= "20 "   id= "ScrollText "> 
 ';
 set_time_limit(0);
ob_end_flush();
for($i = 0; $i<100000; $i++){
     $runtime->start();
    sleep(1);
    //usleep(1000000);
    echo $i."\n";
    flush();
     $runtime->stop(); 
 echo "执行时间: ".$runtime->spent()." 毫秒\n"; 
}

echo '</textarea>';
 
 ?> 

set_time_limit(0);

for($i = 0; $i<100000; $i++){
     $runtime->start();
     echo $i."\n";

     flush();
     ob_flush();
     usleep(250000);
     $runtime->stop(); 
 echo "执行时间: ".$runtime->spent()." 毫秒\n"; 
}
ob_end_flush();