Parse js arrays in ruby

Question

Hi All,

i've js file that holds Array objects and data assigns

var A_1_val = new Array(7);
var B_1_txt = new Array(7);         

A_1_val[0] = '111';
B_1_txt[0] = 'utf8_content';

A_1_val[1] = '222';
B_1_txt[1] = 'bar';

etc..

need to get these arrays in ruby.

found http://github.com/jbarnette/johnson, but it can't correctly return an array object

another way is to eval js in ruby, similar to

1. get name of arrays

2. cut arrays initialize from js

3. ruby eval

   A_1_val[0] = '111'

   B_1_txt[0] = 'utf8_content'

both ways are sucks. maybe you can suggests any ideas

thanks

Answer 1

The easiest way to pass arrays (and a lot of other complex data structures) cross-language is with JSON. Use this to encode the array using JavaScript: http://www.json.org/js.html.

This will encode the array in a format that any langauge that supports JSON can use.

Use this: http://flori.github.com/json/ or this: http://github.com/brianmario/yajl-ruby to decode it with Ruby:

Answer 2

You can use a JSON string to marshal the data between javascript and ruby:

#!/usr/bin/env ruby

require 'johnson'
require 'open-uri'
require 'yajl'

# Grab the source to the Javascript JSON implementation
json_js = open('http://www.json.org/json2.js').read
# Strip that silly alert at the top of the file
json_js.gsub!(/^(alert.*)$/, '/* \1 */')

# This is some Javascript you wanted to get something from
some_js = <<-EOF
var A_1_val = new Array(7);
var B_1_txt = new Array(7);         

A_1_val[0] = '111';
B_1_txt[0] = 'Ähtäri';

A_1_val[1] = 'Barsebäck slott';
B_1_txt[1] = '新宿区';
EOF

result = Johnson.evaluate(<<-EOF)
/* Include the JSON source code */
#{json_js}

/* Include the source code you wanted to get something from */
#{some_js}

/* Turn the things you wanted out into a string */
JSON.stringify([ A_1_val, B_1_txt ])
EOF

# Get the result back in ruby
ruby_result = Yajl::Parser.parse(result)

# Do something with it
puts ruby_result.inspect

which gives the output:

[["111", "Barseb\303\244ck slott", nil, nil, nil, nil, nil], ["\303\204ht\303\244ri", "\346\226\260\345\256\277\345\214\272", nil, nil, nil, nil, nil]]