helpers.js

/*
 * JavaScript tracker for Snowplow: Snowplow.js
 * 
 * Significant portions copyright 2010 Anthon Pang. Remainder copyright 
 * 2012-2014 Snowplow Analytics Ltd. All rights reserved. 
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are 
 * met: 
 *
 * * Redistributions of source code must retain the above copyright 
 *   notice, this list of conditions and the following disclaimer. 
 *
 * * Redistributions in binary form must reproduce the above copyright 
 *   notice, this list of conditions and the following disclaimer in the 
 *   documentation and/or other materials provided with the distribution. 
 *
 * * Neither the name of Anthon Pang nor Snowplow Analytics Ltd nor the
 *   names of their contributors may be used to endorse or promote products
 *   derived from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
;(function () {

	var 
		lodash = require('./lodash'),

		object = typeof exports !== 'undefined' ? exports : this; // For eventual node.js environment support

	/*
	 * UTF-8 encoding
	 */
	object.encodeUtf8 = function (argString) {
		return unescape(decodeURIComponent(argString));
	}

	/**
	 * Cleans up the page title
	 */
	object.fixupTitle = function (title) {
		if (!lodash.isString(title)) {
			title = title.text || '';

			var tmp = document.getElementsByTagName('title');
			if (tmp && !lodash.isUndefined(tmp[0])) {
				title = tmp[0].text;
			}
		}
		return title;
	}

	/*
	 * Extract hostname from URL
	 */
	object.getHostName = function (url) {
		// scheme : // [username [: password] @] hostname [: port] [/ [path] [? query] [# fragment]]
		var e = new RegExp('^(?:(?:https?|ftp):)/*(?:[^@]+@)?([^:/#]+)'),
			matches = e.exec(url);

		return matches ? matches[1] : url;
	}

	/*
	 * Fix-up URL when page rendered from search engine cache or translated page.
	 * TODO: it would be nice to generalise this and/or move into the ETL phase.
	 */
	object.fixupUrl = function (hostName, href, referrer) {
		/*
		 * Extract parameter from URL
		 */
		function getParameter(url, name) {
			// scheme : // [username [: password] @] hostname [: port] [/ [path] [? query] [# fragment]]
			var e = new RegExp('^(?:https?|ftp)(?::/*(?:[^?]+)[?])([^#]+)'),
				matches = e.exec(url),
				f = new RegExp('(?:^|&)' + name + '=([^&]*)'),
				result = matches ? f.exec(matches[1]) : 0;

			return result ? decodeURIComponent(result[1]) : '';
		}

		if (hostName === 'translate.googleusercontent.com') {		// Google
			if (referrer === '') {
				referrer = href;
			}
			href = getParameter(href, 'u');
			hostName = object.getHostName(href);
		} else if (hostName === 'cc.bingj.com' ||					// Bing
				hostName === 'webcache.googleusercontent.com' ||	// Google
				hostName.slice(0, 5) === '74.6.') {					// Yahoo (via Inktomi 74.6.0.0/16)
			href = document.links[0].href;
			hostName = object.getHostName(href);
		}
		return [hostName, href, referrer];
	}

	/*
	 * Fix-up domain
	 */
	object.fixupDomain = function (domain) {
		var dl = domain.length;

		// remove trailing '.'
		if (domain.charAt(--dl) === '.') {
			domain = domain.slice(0, dl);
		}
		// remove leading '*'
		if (domain.slice(0, 2) === '*.') {
			domain = domain.slice(1);
		}
		return domain;
	}

	/*
	 * Get page referrer
	 */
	object.getReferrer = function () {

		var referrer = '';
		
		var fromQs = object.fromQuerystring('referrer', window.location.href) ||
		object.fromQuerystring('referer', window.location.href);

		// Short-circuit
		if (fromQs) {
			return fromQs;
		}

		try {
			referrer = window.top.document.referrer;
		} catch (e) {
			if (window.parent) {
				try {
					referrer = window.parent.document.referrer;
				} catch (e2) {
					referrer = '';
				}
			}
		}
		if (referrer === '') {
			referrer = document.referrer;
		}
		return referrer;
	}

	/*
	 * Cross-browser helper function to add event handler
	 */
	object.addEventListener = function (element, eventType, eventHandler, useCapture) {
		if (element.addEventListener) {
			element.addEventListener(eventType, eventHandler, useCapture);
			return true;
		}
		if (element.attachEvent) {
			return element.attachEvent('on' + eventType, eventHandler);
		}
		element['on' + eventType] = eventHandler;
	}

	/*
	 * Return value from name-value pair in querystring 
	 */
	object.fromQuerystring = function (field, url) {
		var match = RegExp('^[^#]*[?&]' + field + '=([^&#]*)').exec(url);
		if (!match) {
			return null;
		}
		return decodeURIComponent(match[1].replace(/\+/g, ' '));
	}

}());