שינוי גליון הCSS בעזרת javascript

הנה הקוד
ar expDays = 9999;  // How many days to remember the setting
var standardStyle = '2'; // This is the number of your standard style sheet; this will be used when the user did not do anything.
var nameOfCookie = 'switchstyle'; // This is the name of the cookie that is used.
var urlToCSSDirectory = "; // This is the URL to your directory where your .css files are placed on your site.  For example:
var ScreenCSS_1 = 'classic.css';
var ScreenCSS_2 = 'hightech.css';
var ScreenCSS_3 = 'screen_3.css';
// This is the main function that does all the work
function switchStyleOfUser(){
    var fontSize = GetCookie(nameOfCookie);
    if (fontSize == null) {
        fontSize = standardStyle;
    }

    if (fontSize == "1") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + ' ' + ScreenCSS_1 + '" media="screen">'); }
    if (fontSize == "2") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + ScreenCSS_2 + '" media="screen">'); }
    if (fontSize == "3") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + ScreenCSS_3 + '" media="screen">'); }

    var fontSize = "";
    return fontSize;
}

var exp = new Date();
exp.setTime(exp.getTime() + (expDays*24*60*60*1000));

function getCookieVal (offset) {
    var endstr = document.cookie.indexOf (";", offset);
    if (endstr == -1)
    endstr = document.cookie.length;
    return unescape(document.cookie.substring(offset, endstr));
}

// Function to get the settings of the user
function GetCookie (name) {
    var arg = name + "=";
    var alen = arg.length;
    var clen = document.cookie.length;
    var i = 0;
    while (i < clen) {
        var j = i + alen;
        if (document.cookie.substring(i, j) == arg)
        return getCookieVal (j);
        i = document.cookie.indexOf(" ", i) + 1;
        if (i == 0) break;
    }
    return null;
}

function SetCookie (name, value) {
    var argv = SetCookie.arguments;
    var argc = SetCookie.arguments.length;
    var expires = (argc > 2) ? argv[2] : null;
    var path = (argc > 3) ? argv[3] : null;
    var domain = (argc > 4) ? argv[4] : null;
    var secure = (argc > 5) ? argv[5] : false;
    document.cookie = name + "=" + escape (value) +
    ((expires == null) ? "" : ("; expires=" + expires.toGMTString())) +
    ((path == null) ? "" : ("; path=" + path)) +
    ((domain == null) ? "" : ("; domain=" + domain)) +
    ((secure == true) ? ";

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