lib/passport-http/strategies/digest.js
function nonce(len) {
  var buf = []
    , chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
    , charlen = chars.length;

  for (var i = 0; i < len; ++i) {
    buf.push(chars[Math.random() * charlen | 0]);
  }

  return buf.join('');
}
function nonce(len) {
  var buf = []
    , chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
    , charlen = chars.length;

  for (var i = 0; i < len; ++i) {
    buf.push(chars[Math.random() * charlen | 0]);
  }

  return buf.join('');
}
function nonce ( len ) { var buf = [ ] , chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789' , charlen = chars . length ; for ( var i = 0 ; i < len ; ++ i ) { buf . push ( chars [ Math . random ( ) * charlen | 0 ] ) ; } return buf . join ( '' ) ; }
Return a unique nonce with the given `len`.

utils.uid(10);
// => "FDaS435D2z"

CREDIT: Connect -- utils.uid
https://github.com/senchalabs/connect/blob/1.7.1/lib/utils.js

@param {Number} len
@return {String}
@api private
Return a unique nonce with the given len .