CasperJS script to retrieve keyword occurence positions within a given page

kw-positions.js

var casper = require('casper').create();
var positions = [];
var kw = 'JSON';

casper.start('http://phantomjs.org/', function() {
    var pageHeight = this.evaluate(function() {
        return document.body.scrollHeight;
    });
    if (pageHeight < 1) {
        this.echo('no page height', 'ERROR').exit();
    }
    positions = this.evaluate(function(kw, pageHeight) {
        var elements = __utils__.getElementsByXPath("//*[contains(child::text(),'" + kw + "')]");
        return [].map.call(elements, function(element) {
            if (element.nodeName !== "script") {
                var position = element.getBoundingClientRect().top;
                return {
                    position: position,
                    percentage: Math.round((position * 100 / pageHeight) * 100) / 100,
                    tag: element.nodeName,
                    text: element.innerText
                };
            }
        });
    }, {
        kw: kw, pageHeight: pageHeight
    });
});

casper.run(function() {
    require('utils').dump(positions);
    this.exit();
});

$ casperjs kw-positions.js
[
    {
        "attributes": [],
        "percentage": 87.65,
        "position": 738,
        "tag": "P",
        "text": "PhantomJS can also integrate with webservices (XML, JSONP, YQL) and with test frameworks (Jasmine, QUnit). See more examples"
    }
]