[wolco]

For someone who hasn't opened the app in three years going through the upgrading process for each major version/minor high version would be more difficult vs rewriting for most smaller components.

To the parent's parent's point Javascript has evolved since 2015 and comparing what a 2015 app looks like to a 2018 app is day and night.

[brianvaughn]

Upgrading any project after 3 years of inactivity would be difficult, regardless of framework.

I did not mean to imply that you would need to step through every minor version though. I was just saying that- if you were using e.g. 15, update to the latest 15 release (15.6.2) and fixing warnings in it before updating to 16.