gecko-dev/devtools/shared/acorn/UPGRADING.md

Assuming that acorn's dependencies have not changed, to upgrade our tree's acorn to a new version:

1. Clone the acorn repository, and check out the version you want to upgrade to:

   $ git clone https://github.com/marijnh/acorn.git
   $ cd acorn
   $ git checkout <version>
   

2. Make sure that all tests pass:

   $ npm install .
   $ npm test
   

   If there are any test failures, do not upgrade to that version of acorn!

3. Copy acorn.js to our tree:

   $ cp acorn.js /path/to/mozilla-central/devtools/shared/acorn/acorn.js
   

4. Copy acorn_loose.js to our tree:

   $ cp acorn_loose.js /path/to/mozilla-central/devtools/shared/acorn/acorn_loose.js
   

5. Copy util/walk.js to our tree:

   $ cp util/walk.js /path/to/mozilla-central/devtools/shared/acorn/walk.js
   

6. Check and see if javascript pretty-printing and scratchpad work without any errors. As of version 2.6.4 we need to comment out lines in acorn_loose.js that attempt to extend the acorn object, like acorn.parse_dammit = parse_dammit.