浏览器判断条件

 {
        ie      : !!window.ActiveXObject,
        ie6     : document.all && !window.XMLHttpRequest,
        ie7     : document.all && window.XMLHttpRequest && !document.querySelector,
        ie8     : document.all && document.querySelector && !document.addEventListener,
        ie9     : document.all && document.addEventListener && !window.atob,
        ie10    : document.all && window.atob,
        ie11    : ‘-ms-scroll-limit‘ in document.documentElement.style && ‘-ms-ime-align‘ in document.documentElement.style,
        chrome  : !!window.chrome && window.chrome.webstore,
        firefox : !!window.sidebar,
        safari  : /constructor/i.test(window.HTMLElement),
        opera   : !!window.opera || /opera|opr/i.test(navigator.userAgent)
    }