use strict;
my $str = 'callbackProxy({"7103/usatoday/high_impact/entertainment/main":{"_type_":"html","_expandable_":false,"_html_":"\\x3chtml\\x3e\\x3chead\\x3e\\x3cstyle\\x3e\\x3c!--\\na:link { color: #000000 }a:visited { color: #000000 }a:hover { color: #000000 }a:active { color: #000000 } --\\x3e\\x3c/style\\x3e\\x3cscript\\x3e\\x3c!--\\n(function(){var d\\x3d{};window.ss\\x3dfunction(a){void 0!\\x3d\\x3dd[a]?d[a]++:d[a]\\x3d1;var e\\x3ddocument.getElementById(a),b\\x3dd[a];if(window.css)css(a,\\x22nm\\x22,b,void 0,void 0)';
my $regex = qr/\\x/p;
my $subst = '\\u00';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html