Calling methods in javascript through ruby

This is because your str object above is defined as an Array with 1 member, which is a Hash, which has several key/value pairs, the last of which is "projects", whose value is an Array with 1 member, which is a Hash.

IT is not yet a JSON string.

To use JSON functionality, you normally need to …

require "json"

… but I think SketchUp loads it up at startup anyway,…
but you should still “require” it so as to declare a dependency.

Then to produce a JSON string that you wish to send to a HtmlDialog, to produce a JS Object (which is similar to a Ruby OpenStruct,) or a JS Array, you start on the Ruby side with a Hash or OpenStruct, or a Ruby Array

hash = {
      {"project_id"=>310, "name"=>"26Dec", "description"=>""}

# Create the JSON string ...
json_str = hash.to_json # uses double quotes

# Pass the JSON string to a web dialog ...

… then on the JS side something like … (untested)

// JavaScript global variable
var ProjectList = null;

function set_projects( json_str ) {
    ProjectList = JSON.parse(json_str);

function task() {
    if (ProjectList.org_id == 54) {
        // do some task
        if (ProjectList.projects[0].project_id == 310) {
            // Hey we are getting somewhere ...

So, it is important to realize that Ruby Arrays are converted to JS Arrays, …
and Ruby Hashes converted to JS Objects. (This is why is is called JavaScript Object Notation.)

Then when you get JSON strings back from a webdialog and wish to convert back to Ruby …

hash = JSON::load(json_str)

… or simply use the “smart” JSON::[] method …

hash = JSON[json_str]


The JSON library module


The JS Object object

The JSON Object