Zhris
User
Jul 23, 2010, 1:22 PM
Post #2 of 2
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Re: [brsaran] is there any way to clear the HTML output printed by CGI perl
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Hey,
When you refer to "download", I nearly assume that you are physically downloading a file through your browser download dialog. If I am right in saying, you are "reading" data from a database, and whilst the process takes place you would like to dynamically output its progress.
Using CGI alone, this wouldn't be possible (theres no way to clear the screen, without "re-opening" the page). However, although i've never tried, your task would be possible with a client-side language (javascript).
Non-dynamically, you would print output like the following:
#i.e. in a loop
print "$message\n";
#Outputs:
for ex: "1/30 downloading"
for ex: "2/30 downloading"
for ex: "3/30 downloading"
etc
Dynamically, you would print a block of javascript with code inside that calls a function elsewhere, passing perl variable:
#i.e. in a loop
print "<script type=\"text/javascript\">progress('$message');</script>\n";
#Outputs (last loop iteration):
for ex: "30/30 downloading"
Although it may look as if its only outputted 1 line, its actually outputted the javascript block multiple times, but is only visible in the source code.
Anyway, using this theory, I wrote a quick/basic example of how its done. I tested in Firefox 3.6.6 and Internet Explorer 8 only:
#! /usr/bin/perl
use strict;
use CGI ':standard';
use CGI::Carp qw/fatalsToBrowser warningsToBrowser/;
print "Content-type: text/html\n\n";
##########
print qq(
<html>
<head>
<title>CGI Dynamic Progress</title>
<script type="text/javascript">
function Progress(message) {
var e;
if (document.getElementById) { e = document.getElementById("progressdiv"); }
else if (document.all) { e = document.all["progressdiv"]; }
else if (document.layers) { e = document.layers["progressdiv"]; }
e.innerHTML = message;
}
</script>
</head>
<body>
<div id="progressdiv"></div>
);
##########
for (1 .. 1000) {
my $message = ($_ < 1000) ? "Loop iteration: $_" : "Finished";
print "<script type=\"text/javascript\">Progress('$message');</script>\n";
}
##########
print qq(
</body>
</html>
);
Hope this helps,
Chris
Edit: I found a very similar script. I have edited the javascript to ensure its more browser compliant.
(This post was edited by Zhris on Jul 23, 2010, 4:11 PM)
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