function getUuid(){    var len=32;//32长度    var radix=16;//16进制    var chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('');    var uuid = [], i;    radix = radix || chars.length;    if (len) {        for (i = 0; i < len; i++)uuid[i] = chars[0 | Math.random() * radix];    } else {        var r;        uuid[8] = uuid[13] = uuid[18] = uuid[23] = '-';        uuid[14] = '4';        for (i = 0; i < 36; i++) {            if (!uuid[i]) {                r = 0 | Math.random() * 16;                uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r];            }        }    }    return uuid.join('');}function bytesToSize(bytes) {    if (bytes === 0) return '0 B';    var k = 1024;    sizes = ['B','KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];    i = Math.floor(Math.log(bytes) / Math.log(k));    return (bytes / Math.pow(k, i)) + ' ' + sizes[i];}