l10n.js

/*
 * l10n.js
 * 2016-05-17
 * 
 * By Eli Grey, http://eligrey.com
 * Licensed under the MIT License
 *   See https://github.com/eligrey/l10n.js/blob/master/LICENSE.md
 */

/*global XMLHttpRequest, setTimeout, document, navigator, ActiveXObject*/

/*! @source http://purl.eligrey.com/github/l10n.js/blob/master/l10n.js*/

(function () {
"use strict";

var
  undef_type = "undefined"
, string_type = "string"
, nav = self.navigator
, String_ctr = String
, has_own_prop = Object.prototype.hasOwnProperty
, load_queues = {}
, localizations = {}
, FALSE = !1
, TRUE = !0
// the official format is application/vnd.oftn.l10n+json, though l10n.js will also
// accept application/x-l10n+json and application/l10n+json
, l10n_js_media_type = /^\s*application\/(?:vnd\.oftn\.|x-)?l10n\+json\s*(?:$|;)/i
, XHR

// property minification aids
, $locale = "locale"
, $default_locale = "defaultLocale"
, $to_locale_string = "toLocaleString"
, $to_lowercase = "toLowerCase"

, array_index_of = Array.prototype.indexOf || function (item) {
	var
	  len = this.length
	, i   = 0
	;
	
	for (; i < len; i++) {
		if (i in this && this[i] === item) {
			return i;
		}
	}
	
	return -1;
}
, request_JSON = function (uri) {
	var req  = new XHR(),
		data = {};
	
	// sadly, this has to be blocking to allow for a graceful degrading API
	req.open("GET", uri, FALSE);
	req.send(null);
	
	// Status codes can be inconsistent across browsers so we simply try to parse
	// the response text and catch any errors. This deals with failed requests as
	// well as malformed json files.
	try {
		data = JSON.parse(req.responseText);
	} catch(e) {
		// warn about error without stopping execution
		setTimeout(function () {
			// Error messages are not localized as not to cause an infinite loop
			var l10n_err = new Error("Unable to load localization data: " + uri);
			l10n_err.name = "Localization Error";
			throw l10n_err;
		}, 0);
	}

	return data;
}
, load = String_ctr[$to_locale_string] = function (data) {
	// don't handle function.toLocaleString(indentationAmount:Number)
	if (arguments.length > 0 && typeof data !== "number") {
		if (typeof data === string_type) {
			load(request_JSON(data));
		} else if (data === FALSE) {
			// reset all localizations
			localizations = {};
		} else {
			// Extend current localizations instead of completely overwriting them
			var locale, localization, message;
			for (locale in data) {
				if (has_own_prop.call(data, locale)) {
					localization = data[locale];
					locale = locale[$to_lowercase]();
					
					if (!(locale in localizations) || localization === FALSE) {
						// reset locale if not existing or reset flag is specified
						localizations[locale] = {};
					}
					
					if (localization === FALSE) {
						continue;
					}
					
					// URL specified
					if (typeof localization === string_type) {
						if (String_ctr[$locale][$to_lowercase]().indexOf(locale) === 0) {
							localization = request_JSON(localization);
						} else {
							// queue loading locale if not needed
							if (!(locale in load_queues)) {
								load_queues[locale] = [];
							}
							load_queues[locale].push(localization);
							continue;
						}
					}
					
					for (message in localization) {
						if (has_own_prop.call(localization, message)) {
							localizations[locale][message] = localization[message];
						}
					}
				}
			}
		}
	}
	// Return what function.toLocaleString() normally returns
	return Function.prototype[$to_locale_string].apply(String_ctr, arguments);
}
, process_load_queue = function (locale) {
	var
	  queue = load_queues[locale]
	, i = 0
	, len = queue.length
	, localization
	;
	
	for (; i < len; i++) {
		localization = {};
		localization[locale] = request_JSON(queue[i]);
		load(localization);
	}
	
	delete load_queues[locale];
}
, use_default
, localize = String_ctr.prototype[$to_locale_string] = function () {
	var
	  using_default = use_default
	, current_locale = String_ctr[using_default ? $default_locale : $locale]
	, parts = current_locale[$to_lowercase]().split("-")
	, i = parts.length
	, this_val = this.valueOf()
	, locale
	;

	use_default = FALSE;
	
	// Iterate through locales starting at most-specific until a localization is found
	do {
		locale = parts.slice(0, i).join("-");
		// load locale if not loaded
		if (locale in load_queues) {
			process_load_queue(locale);
		}
		if (locale in localizations && this_val in localizations[locale]) {
			return localizations[locale][this_val];
		}
	}
	while (i--);
	
	if (!using_default && String_ctr[$default_locale]) {
		use_default = TRUE;
		return localize.call(this_val);
	}

	return this_val;
}
;

if (typeof XMLHttpRequest === undef_type && typeof ActiveXObject !== undef_type) {
	var AXO = ActiveXObject;
	
	XHR = function () {
		try {
			return new AXO("Msxml2.XMLHTTP.6.0");
		} catch (xhrEx1) {}
		try {
			return new AXO("Msxml2.XMLHTTP.3.0");
		} catch (xhrEx2) {}
		try {
			return new AXO("Msxml2.XMLHTTP");
		} catch (xhrEx3) {}
	
		throw new Error("XMLHttpRequest not supported by this browser.");
	};
} else {
	XHR = XMLHttpRequest;
}

String_ctr[$default_locale] = String_ctr[$default_locale] || "";
if (!String_ctr[$locale]) {
	String_ctr[$locale] = nav && (nav.language || nav.userLanguage) || "";
}

if (typeof document !== undef_type) {
	var
	  elts = document.getElementsByTagName("link")
	, i = elts.length
	, localization
	;
	
	while (i--) {
		var
		  elt = elts[i]
		, rel = (elt.getAttribute("rel") || "")[$to_lowercase]().split(/\s+/)
		;
		
		if (l10n_js_media_type.test(elt.type)) {
			if (array_index_of.call(rel, "localizations") !== -1) {
				// multiple localizations
				load(elt.getAttribute("href"));
			} else if (array_index_of.call(rel, "localization") !== -1) {
				// single localization
				localization = {};
				localization[(elt.getAttribute("hreflang") || "")[$to_lowercase]()] =
					elt.getAttribute("href");
				load(localization);
			}
		}
	}
}

}());