網(wǎng)站多出的一段js代碼

是什么意思？

< script data - cfhash = 'f9e31'type = "text/javascript" >
/* <![CDATA[ */
!
function(t, e, r, n, c, a, p) {
    try {
        t = document.currentScript ||
        function() {
            for (t = document.getElementsByTagName('script'), e = t.length; e--;) if (t[e].getAttribute('data-cfhash')) return t[e]
        } ();
        if (t && (c = t.previousSibling)) {
            p = t.parentNode;
            if (a = c.getAttribute('data-cfemail')) {
                for (e = '', r = '0x' + a.substr(0, 2) | 0, n = 2; a.length - n; n += 2) e += '%' + ('0' + ('0x' + a.substr(n, 2) ^ r).toString(16)).slice( - 2);
                p.replaceChild(document.createTextNode(decodeURIComponent(e)), c)
            }
            p.removeChild(t)
        }
    } catch(u) {}
} ()
/* ]]> */
< /script>/