web scraping global javascript vars in nodejs

getvars.js

const Nightmare = require('nightmare')
const nightmare = Nightmare({
//  show: true
});

var url = process.argv[2] || 'http://labs.easyblog.it/',
    prop = process.argv[3] || undefined;

Object.byString = function(o, s) {
    
    if(!s) return o;

    s = s.replace(/\[(\w+)\]/g, '.$1'); // convert indexes to properties
    s = s.replace(/^\./, '');           // strip a leading dot
    var a = s.split('.');
    for (var i = 0, n = a.length; i < n; ++i) {
        var k = a[i];
        if (k in o) {
            o = o[k];
        } else {
            return;
        }
    }
    return o;
}

nightmare
.goto(url)
//.wait('#content')
.evaluate(function() {
  return this
})
.end()
.then(function(window) {

    var o = Object.byString(window, prop);

    console.log( JSON.stringify(o,null,4) );

});