JS利用Cookie切换网页样式方案

var styleShow = ["blackgreen", "purple"];
var path = "/";
var StyleSwitch = {
  //设置样式
  setStyleSheet: function (StyleName) {
    var i, a, main;
    for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) {
      if (a.getAttribute("rel").indexOf("Style") != -1 && a.getAttribute("title")) {
        a.disabled = true;
        if (a.getAttribute("title") == StyleName) {
          a.disabled = false;
          this.setCookie("Style", StyleName);
        }
      }
    }
  },
  //获取当前使用样式
  getStyleSheet: function () {
    var i, a;
    for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) {
      if (a.getAttribute("rel").indexOf("Style") != -1 && a.getAttribute("title") && !a.disabled) {
        return a.getAttribute("title");
      }
    }
    return null;
  },
  //获取默认样式
  getPreferredStyleSheet: function () {
    var i, a;
    for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) {
      if (a.getAttribute("rel").indexOf("Style") != -1
    && a.getAttribute("rel").indexOf("alt") == -1
    && a.getAttribute("title")
    ) {
        return a.getAttribute("title");
      }
    }
    return null;
  },
  //获取cookie
  getCookie: function (name) {
    var cookieName = encodeURIComponent(name) + "=",
    cookieStart = document.cookie.indexOf(cookieName),
    cookieValue = null;
    if (cookieStart > -1) {
      var cookieEnd = document.cookie.indexOf(";", cookieStart);
      if (cookieStart == -1) {
        alert(-2);
        cookieEnd = document.cookie.length;
      }
      cookieValue = decodeURIComponent(document.cookie.substring(cookieStart + cookieName.length, cookieEnd));
    }
    for (var i = 0; i < styleShow.length; i++) {
      if (cookieValue == styleShow[i]) {
        alert(styleShow[i]);
        return styleShow[i];
      }
    }
    return styleShow[0];
  },
  //生成cookie
  //name cookie名
  //value 值
  //expires 过期时间
  //path 路径
  setCookie: function (name, value, expires, path, domain, secure) {
    var cookieText = encodeURIComponent(name) + "=" + encodeURIComponent(value) + ";";
    if (expires instanceof Date) {
      cookieText += "expires=" + expires.toGMTString();
    }
    if (path) {
      cookieText += ";path=" + path;
    }
    if (domain) {
      cookieText += ";domain=" + domain;
    }
    if (secure) {
      cookieText += ";secure";
    }
    document.cookie = cookieText;
  },
  //重置cookie
  unsetCookie: function (name, path, domain, secure) {
    this.set(name, "", new Date(0), path, domain, screen);
  }
};