Get random bytes in Javascript (Browser/Node)

get_random_bytes.js

let getRandomBytes = (
  (typeof self !== 'undefined' && (self.crypto || self.msCrypto))
    ? function() { // Browsers
        var crypto = (self.crypto || self.msCrypto), QUOTA = 65536;
        return function(n) {
          var a = new Uint8Array(n);
          for (var i = 0; i < n; i += QUOTA) {
            crypto.getRandomValues(a.subarray(i, i + Math.min(n - i, QUOTA)));
          }
          return a;
        };
      }
    : function() { // Node
        return require("crypto").randomBytes;
      }
)();
  
// Get an array of 18 random bytes where each byte is an integer from range [0,255] inclusive, where [0,255] 
// is the range of 8-bit unsigned integers from `new Uint8Array(n)`
let aesKey = getRandomBytes(18)

// Then you can do something like  `_.shuffle(aesKey).join('');`