in reply to Re^2: Accessing javascript variable from perl
in thread Accessing javascript variable from perl

The errorMessages are explicitly given!

HINT: var denotes a lexical var inside a function°, it only becomes global* if used outside.

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

updates

°) mostly like my in Perl except for the hoisting effect

*) in this case it behaves mostly like our in Perl

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Re^4: Accessing javascript variable from perl
by frazap (Monk) on Jun 18, 2019 at 07:18 UTC
    With the file jello.jshello.js 
    var leg = {
aa: "Hello from javascript"
}

function to_json() {
   return JSON.stringify(leg);
}

    [download]
    And the file perl.pl 
    use strict;
use warnings;
use WWW::Mechanize::PhantomJS;
my $js = WWW::Mechanize::PhantomJS->new(launch_exe=> 'C:/prog/phantomj
+s/bin/phantomjs.exe');
$js->get_local("hello.js");
#$js->update_html('<script src="hello.js" type="text/javascript"></scr
+ipt>');
#print $js->content;
#my ($val, $type) = $js->eval_in_page('JSON.stringify(window.leg);');
my ($val, $type) = $js->eval_in_page('to_json()');
print "val: $val, type: $type\n";

    [download]
    I can't have any meaningfull result from calling eval_in_page either on the leg var directly or via the function.

    Can you show me how to have this working ?

    Thanks

    Update without phantomjs 
    use strict;
use warnings;
use Log::Log4perl qw(:easy);
Log::Log4perl->easy_init($ERROR);
use WWW::Mechanize::Chrome;
my $js = WWW::Mechanize::Chrome->new(report_js_errors=>1);
$js->get_local("hello.js");
#$js->update_html('<script src="hello.js" type="text/javascript"></scr
+ipt>');
#print $js->content;
#my ($val, $type) = $js->eval_in_page('JSON.stringify(window.leg);');
my ($val, $type) = $js->eval_in_page('to_json()');
print "val: $val, type: $type\n";

    [download]

    This gives undef for $val whatever I'm calling: the to_json() function or JSON.stringify directly.

[reply]
[d/l]
[select]
      hello != jello

      > I can't have any meaningfull result ...

      Which error message do you get?

      I don't have phantomjs installed, so please provide a reproducible example.

      UPDATE

      I ran your JS code in the browser's console and it works for me:

      > var leg = {
aa: "Hello from javascript"
}

function to_json() {
   return JSON.stringify(leg);
}

< undefined

> JSON.stringify(leg);

< "{\"aa\":\"Hello from javascript\"}"

> to_json()

< "{\"aa\":\"Hello from javascript\"}"

      [download]

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

[reply]
[d/l]
      regarding your update:

      Neither do I have WWW::Mechanize::Chrome installed.

      My suggestions are

      • to make sure your JS is really executed (add an alert to show)
      • and this before you try eval_in_page (you could play around with sleep or a similar wait mechanism)
      HTH!

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

[reply]
        HTH

        Yes, it did: adding an alert("hello from js"); in the js file show me that a (the only ?) way to have it executed, was to load an existing html file. Using $js->modify_html('<script src="hello.js" type="text/javascript"></script>')on a blank page did not run the js file.

        So, I have to load this

        <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1
+">
<title>test</title>
<script src="hello.js"></script>
</head>
<body>
</body

        [download]
        Then, the following worked: 
        my $js = WWW::Mechanize::PhantomJS->new(launch_exe=> 'C:/prog/phantomj
+s/bin/phantomjs.exe');
#or
#my $js = WWW::Mechanize::Chrome->new(report_js_errors=>1);
$js->get_local("hello.html");
my ($val, $type) = $js->eval_in_page('JSON.stringify(window.leg);');
#or
#my ($val, $type) = $js->eval_in_page('JSON.stringify(leg);');
#or
#my ($val, $type) = $js->eval_in_page('to_json()');
print "val: ", Dumper($val), "type: $type\n";

        [download]

        Thanks

        frazap

[reply]
[d/l]
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