PHP实现通用alert函数的方法

function alert($str,$typ="back",$topwindow="",$tim=100){
  echo "<script>".chr(10);
  if(!empty($str)){
    echo "alert("warning:\n\n{$str}\n\n");".chr(10);
  }
  echo "function _r_r_(){";
  $winname=(!empty($topwindow))?"top":"self";
  switch (strtolower($typ)){
  case "#":
    break;
  case "back":
    echo $winname.".history.go(-1);".chr(10);
    break;
  case "reload":
    echo $winname.".window.location.reload();".chr(10);
    break;
  case "close":
    echo "window.opener=null;window.close();".chr(10);
    break;
  case "function":
    echo "var _t=new function('return {$topwindow}')();_t();".chr(10);
    break;
    //die();
  default:
    if($typ!=""){
      //echo "window.{$winname}.location.href='{$typ}';";
      echo "window.{$winname}.location=('{$typ}');";
    }
  }
  echo "}".chr(10);
  //為防止firefox不執行settimeout
  echo "if(settimeout("_r_r_()",".$tim.")==2){_r_r_();}";
  if($tim==100){
    echo "_r_r_();".chr(10);
  }else{
    echo "settimeout("_r_r_()",".$tim.");".chr(10);
  }
  echo "</script>".chr(10);
  exit();
}