Re^3: CGI javascript AJAX - progress in real time on a web page.

[Anonymous Monk]

Is there not a way to print a whole web page then update elements of it like Ajax does?

Yes, it is called AJAX, and there is no ajax without javascript.

[Caesura]

Hi, Well, I decided to go for the server push method, because :
1. it seemed to work and was simple to do
2. er, no second reason ...
This is what I did, I created an empty div, then filled it with more little div boxes for each thing in the loop. Also I put a span in for a textual N / M status. All on the fly, using JavaScript innerHtml to change elements on the page, just by sending the JavaScript command to the browser.

Seemed to work!

Note that I used =+ to add innerHTML boxes to existing boxes.

main_prog.cgi :

print header;
... etc ...

# Print a div box with a span element to fill in with later JavaScript
+ commands.
#
print "<div id=\"Progress\" class=\"box_div\"> " .
          "   <i>Progress on things </i> : " .
          "   <span id=\"meter\"></span> " .
          "</div>\n";
...
# Loop the loop
#
my $max_things  = scalar (@things);
my $thing_index = 0;
foreach my $thing (@things) {
   $thing_index++;
...
   # Print the current thing into the span meter.
   #
   print <<_EOT_;
<script language=JavaScript type=text/javascript><!--
    document.getElementById('meter').innerHTML ='$thing_index of $max_
+things';
//--></script>
_EOT_

   # Do the things ...
   ...
   if ($status eq "excellent") {

      # Add a small div box with the thing and a tick 
      # image to the main div box - its all floated 
      # left so will fill up nicely.
      #
      print <<_EOT_;
<script language=JavaScript type=text/javascript><!--
    document.getElementById('Progress').innerHTML+='<div class=\"div_o
+k\">Thing $thing_index is excellent<img src=/img/tick.png width=\"10\
+" height=\"10\
"></div>';                              
//--></script>                          
_EOT_   

   } else {

<script language=JavaScript type=text/javascript><!--
    document.getElementById('Progress').innerHTML+='<div class=\"div_n
+otok\">Thing $thing_index is v. bad<img src=/img/cross.png width=\"10
+\" height=\"10\
"></div>';                              
//--></script>                          
_EOT_   

   } # endif excellent

} # end foreach thing


The CSS was :

div.box_div {      
   border: thin solid #000000;
   padding:5px;            
   margin:9px;
   color:#0088FF;
   width:75%;   
   float:left;
}
div.div_ok {           
   border: thin solid #0088FF;
   padding:2px;            
   margin:2px;
   color:#0088FF;
   float:left;  
}               
div.div_notok {        
   border: thin solid #FF0000;
   padding:2px;            
   margin:2px;             
   color:#FF0000;
   float:left;  
}               
            
</style>

So it seems the trick was just to send JavaScript commands to the browser from the Perl CGI.

Not ideal, but seemed to work for IE6 and FF3. Ymmv etc ;)

Hope that's useful for someone.

Cheers,

Caesura