Unescaping JavaScript string

a01 has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks,

I need my Perl script to unescape a JavaScript string literal that is in a <script> tag in HTML code that I need to parse. For example:

<script type="text/javascript">window.open ('https\x3a\x2f\x2fexample.
+com')</script>
[download]

If I capture the string with a regular expression, I get the string:

https\x3a\x2f\x2fexample.com

I need to decode this to:

https://example.com

How do I do this in Perl?

Comment on Unescaping JavaScript string Select or Download Code

Replies are listed 'Best First'.
Re: Unescaping JavaScript string (encode/decode) by Anonymous Monk on Mar 18, 2016 at 04:32 UTC
use JavaScript::HashRef::Decode `#!/usr/bin/perl -- use strict; use warnings; use JavaScript::HashRef::Decode qw/ decode_js /; my $string = q{'https\x3a\x2f\x2fexample.com'}; my $js_hash = "{it:$string}";; my $fromJs = decode_js( $js_hash ) ; dd( $string, $js_hash, $fromJs ); dd( $fromJs->{it} ); __END__ ( "'https\\x3a\\x2f\\x2fexample.com'", "{it:'https\\x3a\\x2f\\x2fexample.com'}", { it => "https://example.com" }, ) "https://example.com"` [download]	[reply] [d/l]
Re: Unescaping JavaScript string by 1nickt (Canon) on Mar 18, 2016 at 04:25 UTC
Hi a01, welcome to the monastery. Your string was encoded to UTF-8, so you need to decode it using the core module Encode. `$ perl -MEncode -E' say Encode::decode_utf8("https\x3a\x2f\x2fexample.com"); ' https://example.com` [download] You may want to refer to perlunitut for an introduction to Unicode processing in Perl. Hope this helps! The way forward always starts with a minimal test.	[reply] [d/l]
Re^2: Unescaping JavaScript string by bart (Canon) on Mar 18, 2016 at 11:35 UTC
`"https\x3a\x2f\x2fexample.com"` That code is useless to the OP. You replaced single quotes (the original Javascript) with double quotes, thereby doing the decoding in the Perl source code. It won't work if the data comes from anywhere else than from the source of the Perl script itself.	[reply] [d/l]
Re^2: Unescaping JavaScript string by Your Mother (Archbishop) on Mar 18, 2016 at 13:39 UTC
It's also important, I feel, to note that this is not necessarily UTF-8. `Latin-1 (ISO 8859-1) \x3a = 58 = : = chr(58) = "\x{3a}" \x2f = 47 = / = chr(47) = "\x{2f}" ASCII: ditto UTF-8: same same Windows-1252: also, also` [download] Unless it's been specifically decoded to UTF-8 (or one of the others) from a known source encoding, or it appeared in a `use utf8` script literally, it is a risky assumption.	[reply] [d/l] [select]
Re^2: Unescaping JavaScript string by Anonymous Monk on Mar 18, 2016 at 04:34 UTC
javascript has more ways to encode strings that Encode::decode_utf8 doesn't handle	[reply]


good chemistry is complicated, and a little bit messy -LW
	PerlMonks