Great post. Mutability in JS makes things very complicated (I recently had a hair pulling bug that modified properties on an unintended object). You know you can also create a constant object with Object.seal(obj) ? Once you pass your object to the seal method, you won't no longer be able to modify its properties.

I have a couple of javascript posts on promises as well...check them out and follow me Hive account@codero

• https://steemit.com/javascript/@codero/simple-explanation-of-javascript-promises
• https://steemit.com/javascript/@codero/handling-multiple-async-operations-in-javascript-with-promise-all