使用Javascript实现随机字符串

　　方法一（其实是毫秒时间数字字符串）： 

function randomString() {
    return '' + new Date().getTime();
}

　　方法二（随机字母数字字符串）： 

var alpha_num_chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz'.split('');

function randomString(length) {

    if (! length) {
        length = Math.floor(Math.random() * alpha_num_chars.length);
    }

    var str = '';
    for (var i = 0; i < length; i++) {
        str += alpha_num_chars[Math.floor(Math.random() * alpha_num_chars.length)];
    }
    return str;
}

// generate a random string of random length
randomString();

// generate a random string of length 8
randomString(8);