Why the names btoa and atob for Base64 encoder decoder functions?

Why are they named btoa() and atob()?#

If you have ever needed to encode text to Base64 or decode a Base64 encoded string to plain text, you should be familiar with the methods btoa() and atob().

Their names might have caught your attention and got you wondering, "Are these random names along the lines of x_to_y and y_to_x? Why are they named so?"

Here is the explanation:

• btoa implies "binary to ASCII"
• atob implies "ASCII to binary"

Here "binary" and "ASCII" are used in a slightly different context.

• ASCII - printable ASCII characters, A to Z, a to z, 0 to 9, +, /, and =, which form the Base64 character set
• Binary - Any printable or non-printable characters

Brendan Eich, the creator of JavaScript explains his decision in this tweet:

Old Unix names, hard to find man pages rn but see https://t.co/lWkceMwFad. The names carried over from Unix into the Netscape codebase. I reflected them into JS in a big hurry in 1995 (after the ten days in May but soon).

— BrendanEich (@BrendanEich) May 21, 2018

References#

1. https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding
2. https://html.spec.whatwg.org/multipage/webappapis.html#atob
3. https://en.wikipedia.org/wiki/Base64