js判断手机是的操作系统

 var browser = {
                 versions: function() {
                     var u = navigator.userAgent,
                     app = navigator.appVersion;
                     return {

                         android: u.indexOf('Android') > -1 || u.indexOf('Linux') > -1,

                         iPhone: u.indexOf('iPhone') > -1 ,                      

                         iPad: u.indexOf('iPad') > -1,
                         iPod: u.indexOf('iPod') > -1,

                     };
                 } (),
                 language: (navigator.browserLanguage || navigator.language).toLowerCase()
             }
             if (browser.versions.iPhone||browser.versions.iPad||browser.versions.iPod)
             {
                 alert("apple")
             }
             else if(browser.versions.android)
             {
                alert("Android");
             }  else{
                 alert("other");
             }