passing Python data to a javascript function

Wed Oct 26 23:51:34 EDT 2011

Chris,

Wow, that seems so simple now that I see it.  I was dancing around that all
day, but just not landing on it.   Thanks so very much for the assist.

--Bill

Final code that works perfectly, passes the value from the Python script to
the javascript correctly:

#!/usr/bin/python
import json, os, cgi, cgitb
cgitb.enable()

pid_data = str(os.getpid())

print "Content-type: text/html"
print

print """
<html>
<head><title>Test Page</title>
<script type="text/javascript">
function showPID(pid){

document.getElementById('txt').innerHTML="js: "+pid;
}
</script>
</head>
<body onload="showPID("""+pid_data+""")">

Hello World!<br><br>
<div id="txt"></div><br>
"""
print "html: "+pid_data+"<br>"
print """
</body>
</html>"""

Output of above code is the following, which is just the PID of the Python
CGI itself at runtime, displayed via javascript and via HTML.
Hello World!

js: 1308

html: 1308

On Wed, Oct 26, 2011 at 21:42, Chris Rebert <clp2 at rebertia.com> wrote:

> On Wed, Oct 26, 2011 at 7:25 PM, Bill Allen <wallenpb at gmail.com> wrote:
>
> The problem is that you're not passing the data at all. You never
> interpolate the pid_data value into the string(s) constituting your
> embedded JavaScript (though you did do it just fine in the pure HTML).
> The Python variable `pid_data` is not somehow magically accessible to
> JavaScript; you must explicitly insert its value somewhere.
>
> <snip>
> > pid_data = str(os.getpid())
> <snip>
> > print """
> <snip>
> > <body onload="showPID(pid_data)">
>
> Change that line to:
> <body onload="showPID("""+pid_data+""")">
>
> As an example, if the PID happens to be 42, then the outputted
> fragment will end up being:
> <body onload="showPID(42)">
>
> As a sidenote, I would recommend using something higher-level than the
> `cgi` module. Python has an abundance of web frameworks and templating
> languages; take your pick.
>
> Cheers,
> Chris
> --
> http://rebertia.com
>
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