How to encode/decode base64 with JS

Execution environment

Chrome ver. 79.0
Confirmation of operation with console of Dev tool

Encoding to base64 is done with the btoa command

btoa("This is a test.")
> "VGhpcyBpcyBhIHRlc3Qu"

To decode a base64 encoded string, use the atob command

atob("VGhpcyBpcyBhIHRlc3Qu")
> "This is a test."