How to retrieve data from Xpath in javascript

How to retrieve data from Xpath in javascript. I am using document for retrieving data. code given below.

when i run that code give empty array i didn't get WHY ????????.

var wgxpath = require('wgxpath');
var jsdom = require("jsdom").jsdom;
var document = jsdom();
var window = document.defaultView;

var url = 'http://www.merriam-webster.com/word-of-the-day/';
var expressionString = '//*[@title]';

jsdom.env({
    html: url,
    done: function(errors, window) {
        var message = "";
        wgxpath.install(window);
        var expression = window.document.createExpression(expressionString);
        var result = expression.evaluate(window.document,0);
        console.log(result);
    }
});