Gmail will block .js file attachments starting February 13, 2017

Gmail currently restricts certain file attachments (e.g. .exe, .msc, and .bat) for security reasons, and starting on February 13, 2017, we will not allow .js file attachments as well. Similar to other restricted file attachments, you will not be able to attach a .js file and an in-product warning will appear, explaining the reason why.

If you still need to send .js files for legitimate reasons, you can use Google Drive, Google Cloud Storage, or other storage solutions to share or send your files.

Launch Details
Release track:
Launching to Rapid release on February 13, 2017, with Scheduled release coming 2 weeks afterward

Editions:
Available to all G Suite editions

Rollout pace:
Full rollout (1-3 days for feature visibility)

Reference by Google.com