判断浏览器版本

// Opera 8.0+
var isOpera = (!!window.opr && !!opr.addons) || !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0; // Firefox 1.0+ var isFirefox = typeof InstallTrigger !== 'undefined'; // Safari 3.0+ "[object HTMLElementConstructor]"  var isSafari = /constructor/i.test(window.HTMLElement) || (function (p) { return p.toString() === "[object SafariRemoteNotification]"; })(!window['safari'] || (typeof safari !== 'undefined' && safari.pushNotification)); // Internet Explorer 6-11 var isIE = /*@cc_on!@*/false || !!document.documentMode; // Edge 20+ var isEdge = !isIE && !!window.StyleMedia; // Chrome 1 - 79 var isChrome = !!window.chrome && (!!window.chrome.webstore || !!window.chrome.runtime); // Edge (based on chromium) detection var isEdgeChromium = isChrome && (navigator.userAgent.indexOf("Edg") != -1); // Blink engine detection var isBlink = (isChrome || isOpera) && !!window.CSS;