This script is capable of being controlled by other scripts. All the helper scripts that are designed for this script uses this special messaging system to control it. I use a localStorage variable to accept commands because it can be used with any script as long as it's on the same domain name. The postMessage way of sending messages is mostly for cross domain messaging so I didn't need that if all scripts are running on mturk.com. At this time I only accept localStorage communication but may accept postMessage in the future.