get dynamic properties in javascript

var tinymce_toolbar = {}
tinymce_toolbar.__default =
{
   script_url: '/cms/libs/js/manual/renders/tiny_mce/tiny_mce.js',  
};
tinymce_toolbar.__simple =
{
   script_url: '/cms/libs/js/manual/renders/tiny_mce/tiny_mce_simple.js',   
};


// Doesn't work
var t = $(this).find('input[name=toolbar]').first().val();
$('.RenderHtmlEditor').tinymce(tinymce_toolbar.t);

// works
var t = $(document).find('input[name=toolbar]').first().val();
$('.RenderHtmlEditor').tinymce(tinymce_toolbar.__default);
$('.RenderHtmlEditor').tinymce(tinymce_toolbar.__simple);

how i do it to be dynamic? Thanks