URL pathname replace for conditional redirects to support multi-language sites

pathnamereplace.js

/* pathnamereplace.js v0.1.2, URL pathname replace for conditional redirects to support multi-language sites, now with cookies and passtrue list. 
 * Author & copyright (c) 2014: Göran Svensson, goran@molnsys.com. MIT license. 
 * Tested with Chrome 36, Firefox 29 and Safari 7.0.5 on OSX. 
 * Tested with Chrome 36 on Xperia V (Android 4.3) and Internet 2.3.6 on Samsung GT-S5360 (Android 2.3.6).
 * Works with any number of path name items and language acronymes. Does not break the back button. 
 * How to use it; add this in your nav menu: javascript:changeLanguage('_se') to switch to swedish version.
 * REQUIRES: CatalystScripts/Java_Cookies.js and country = '{module_visitorcountrycode}'; added 
 * above this script (does not work inside a js file).
 * No bugs have been harmed.
 * To avoid unnecesary reload, build a nav menu for each language with the right path.
 */

var defaultLang = '_en', // has no folder (eg: //features/faqs)
    pathArray = window.location.pathname.split( '/' ), // get the path and split the string on "/"
    langArray = ["_se","_es"], // Do not include the default lang here! You need to have a matching folder under root with the same structure as for the default language (eg: /_se/features/faqs). 
    passtrueArray = ["CampaignProcess.aspx","FormProcessv2.aspx"], // sometimes it is not possible to add language support to a module. Then we do not check language.
    constructPath = window.location.protocol + "//" + window.location.host; 
    pathArray.splice(0,1); // remove the first item which is empty  
var firstPartofPathname = pathArray[0],
    cookieValue = readCookie('selectedLanguage'),
    thepathname = window.location.pathname,
    visitorLanguage = ""; 

switch (country) {
    case 'US':
    visitorLanguage = "_en";
    break;
    case 'SE':
    visitorLanguage = "_se";
    break; 
    case 'UK':
    visitorLanguage = "_en";
    break;  
    case 'ES':
    visitorLanguage = "_es";
    break;      
    default:
    visitorLanguage = defaultLang;
    break;
}

// run it on every request 

if (!checkPassTrue()){
    if (cookieValue!=null){
        changeLanguage(cookieValue);}
        else {
        changeLanguage(visitorLanguage);  
    }
}
// helper function: check if the first path item contains any of the known language acronymes    
function checkLanguage(){ 
    var itemFoundFlag = false;
    if (langArray.indexOf(firstPartofPathname) > -1) itemFoundFlag = true;
    return itemFoundFlag;
} 

// helper function: don´t redirect if the first path contains anything from the passtrue array.   
function checkPassTrue(){ 
    var itemFoundFlag = false;
    if (passtrueArray.indexOf(firstPartofPathname) > -1) itemFoundFlag = true;
    return itemFoundFlag;
} 

// helper function: put the pathname back together with slashes   
function buildPath(theArray){     
    var newPathname = "";
    for (i = 0; i < theArray.length; i++) {
        newPathname += "/";
        newPathname += theArray[i];
    }
    return newPathname;
}   

// main function: changeLanguage takes a language acronyme as an argument and replaces the path name in the URL.    
function changeLanguage(theLanguage){ 
    if (theLanguage == defaultLang){
        if (checkLanguage()){
            // remove the first item 
            pathArray.splice(0,1);
         } 
        // avoid infinite loop
        if (thepathname != buildPath(pathArray)){ 
        // create cookie
        createCookie('selectedLanguage',defaultLang,100);    
        // replace the url 
        window.location.replace(constructPath + buildPath(pathArray));
        }    
        } else if (theLanguage != firstPartofPathname) {
            if (checkLanguage()) {
            // replace the lang in the URL
            pathArray[0] = theLanguage;
            } else if (checkLanguage() == 0) {   
            // add the Language
            pathArray.splice(0, 0, theLanguage);    
            } 
            // avoid infinite loop
            if (thepathname != buildPath(pathArray)){
             // create cookie
            createCookie('selectedLanguage',theLanguage,100);
            // replace the url  
                if (thepathname == "/"){ 
                window.location.replace(constructPath + '/' + theLanguage);
            } else{
                window.location.replace(constructPath + buildPath(pathArray));
                }   
            }    
        } 
}