encode/decode base64 with JS

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."

try/catch es10

An update for developer convience allows the use of try/catch without an explicit e Error reference in the catch call.

Use flatMap() creates a new array with sub-array elements flattened by specified depth.