可以使用lodash uniqueId:

    _.uniqueId([prefix=''])

生成唯一的ID。如果给出了prefix，则ID被追加到它后面。

我只是发现了一个非常好的优雅的解决方案:

Math.random().toString(36).slice(2)

这个实现的注意事项:

This will produce a string anywhere between zero and 12 characters long, usually 11 characters, due to the fact that floating point stringification removes trailing zeros. It won't generate capital letters, only lower-case and numbers. Because the randomness comes from Math.random(), the output may be predictable and therefore not necessarily unique. Even assuming an ideal implementation, the output has at most 52 bits of entropy, which means you can expect a duplicate after around 70M strings generated.

var randomString = function(length) {
  var str = '';
  var chars ='0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz'.split(
      '');
  var charsLen = chars.length;
  if (!length) {
    length = ~~(Math.random() * charsLen);
  }
  for (var i = 0; i < length; i++) {
    str += chars[~~(Math.random() * charsLen)];
  }
  return str;
};

或者根据Jar Jar的建议，这是我在最近的一个项目中使用的方法(以克服长度限制):

var randomString = function (len, bits)
{
    bits = bits || 36;
    var outStr = "", newStr;
    while (outStr.length < len)
    {
        newStr = Math.random().toString(bits).slice(2);
        outStr += newStr.slice(0, Math.min(newStr.length, (len - outStr.length)));
    }
    return outStr.toUpperCase();
};

Use:

randomString(12, 16); // 12 hexadecimal characters
randomString(200); // 200 alphanumeric characters

可以使用lodash uniqueId:

    _.uniqueId([prefix=''])

生成唯一的ID。如果给出了prefix，则ID被追加到它后面。

如果你只想允许特定的字符，你也可以这样做:

function randomString(length, chars) {
    var result = '';
    for (var i = length; i > 0; --i) result += chars[Math.floor(Math.random() * chars.length)];
    return result;
}
var rString = randomString(32, '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ');

下面是一个演示的jsfiddle: http://jsfiddle.net/wSQBx/

另一种方法是使用一个特殊的字符串，告诉函数使用什么类型的字符。你可以这样做:

function randomString(length, chars) {
    var mask = '';
    if (chars.indexOf('a') > -1) mask += 'abcdefghijklmnopqrstuvwxyz';
    if (chars.indexOf('A') > -1) mask += 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
    if (chars.indexOf('#') > -1) mask += '0123456789';
    if (chars.indexOf('!') > -1) mask += '~`!@#$%^&*()_+-={}[]:";\'<>?,./|\\';
    var result = '';
    for (var i = length; i > 0; --i) result += mask[Math.floor(Math.random() * mask.length)];
    return result;
}

console.log(randomString(16, 'aA'));
console.log(randomString(32, '#aA'));
console.log(randomString(64, '#A!'));

小提琴:http://jsfiddle.net/wSQBx/2/

或者，像下面描述的那样使用base36方法，你可以这样做:

function randomString(length) {
    return Math.round((Math.pow(36, length + 1) - Math.random() * Math.pow(36, length))).toString(36).slice(1);
}