采用Javascript 生成随机数

function generateId(length) {

length = length || 10;

var letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';

var s = '';

for (var i = 0; i < length; i++) {

s += letters.charAt(Math.floor(Math.random() * letters.length));

}

return s;

}