判断当前浏览器的类型

You can use the following code to detect the different browsers:
// Check for Chrome
var isChrome = /Chrome/.test(navigator.userAgent) && /Google Inc/.test(navigator.vendor);
// Check for Firefox
var isFirefox = typeof InstallTrigger !== 'undefined';
// Check for Safari
var isSafari = /Safari/.test(navigator.userAgent) && /Apple Computer/.test(navigator.vendor);
// Check for IE 前面那个是ie6-10 后面那个是ie7-11
var isIE = /@cc_on!@/false || !!document.documentMode;
// Check for Opera
var isOpera = (!!window.opr && !!opr.addons) || !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0;