使用php / javascript在谷歌浏览器中更改.js？

Hi :) It is possible to set different javascript files in different browser? I wannna change a JS in Chrome (pc version) I know that is possible with css, so I tryied this code including .js file, but apparently don't work..so I'm asking if there is a diffent way to set .js (if is it possible).

<?php
if ( ereg( "Chrome" , $_SERVER['HTTP_USER_AGENT']) ) {  
echo '<script src="js/developr.inputCHROME.js"></script>';  
}else{  
echo '<script src="js/developr.input.js"></script>';
}
?>

Thank you in advice.

Try

    $user_agent = $_SERVER['HTTP_USER_AGENT']; 

    if (strpos( $user_agent, 'Chrome') !== false)
    {  
          echo '<script src="js/developr.inputCHROME.js"></script>';  
    }else
    {  
          echo '<script src="js/developr.input.js"></script>';
    }