UniqueId.js

// Generate unique IDs for use as pseudo-private/protected names.
// Similar in concept to
// <http://wiki.ecmascript.org/doku.php?id=strawman:names>.
//
// The goals of this function are twofold:
// 
// * Provide a way to generate a string guaranteed to be unique when compared
//   to other strings generated by this function.
// * Make the string complex enough that it is highly unlikely to be
//   accidentally duplicated by hand (this is key if you're using `ID`
//   as a private/protected name on an object).
//
// Use:
//
//     var privateName = ID();
//     var o = { 'public': 'foo' };
//     o[privateName] = 'bar';
const ID = () => {
  // Math.random should be unique because of its seeding algorithm.
  // Convert it to base 36 (numbers + letters), and grab the first 9 characters
  // after the decimal.
  return `_${Math.random().toString(36).substr(2, 9)}`;
};

// use crypto!
const ID = () => {
  const array = new Uint32Array(8);
  window.crypto.getRandomValues(array);
  let str = '';
  for (let i = 0; i < array.length; i++) {
    str += (i < 2 || i > 5 ? '' : '-') + array[i].toString(16).slice(-4);
  }
  return str;
}


// Any length
const ID = (length) => {
    if (!length) {
        length = 8;
    }
    let str = '';
    for (let i = 1; i < length + 1; i = i + 8) {
        str += Math.random().toString(36).substr(2, 10);
    }
    return ('_' + str).substr(0, length);
}