Why were Javascript `atob()` and `btoa()` named like that?

Question

In Javascript, window.atob() method decodes a base64 string and window.btoa() method encodes a string into base64.

Then why weren't they named like base64Decode() and base64Encode()? atob() and btoa() don't make sense because they're not semantic at all.

I want to know the reason.

Answer 1

The atob() and btoa() methods allow authors to transform content to and from the base64 encoding.

In these APIs, for mnemonic purposes, the "b" can be considered to stand for "binary", and the "a" for "ASCII". In practice, though, for primarily historical reasons, both the input and output of these functions are Unicode strings.

From : http://www.w3.org/TR/html/webappapis.html#atob

Answer 2

I know this is old, but it recently came up on Twitter, and I thought I'd share it as it is authoritative.

Me:

@BrendanEich did you pick those names?

Him:

Old Unix names, hard to find man pages rn but see https://www.unix.com/man-page/minix/1/btoa/ …. 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).

In case the Minix link breaks, here's the man page content:

BTOA(1)                                           BTOA(1)  NAME        btoa - binary to ascii conversion  SYNOPSIS        btoa [-adhor] [infile] [outfile]  OPTIONS        -a     Decode, rather than encode, the file         -d     Extracts repair file from diagnosis file         -h     Help menu is displayed giving the options         -o     The obsolete algorithm is used for backward compatibility         -r     Repair a damaged file  EXAMPLES        btoa <a.out >a.btoa # Convert a.out to ASCII         btoa -a <a.btoa >a.out                # Reverse the above  DESCRIPTION        Btoa  is  a  filter that converts a binary file to ascii for transmission over a telephone        line.  If two file names are provided, the first in used for input and the second for out-        put.   If  only one is provided, it is used as the input file.  The program is a function-        ally similar alternative to uue/uud, but the encoding is completely different.  Since both        of  these are widely used, both have been provided with MINIX.  The file is expanded about        25 percent in the process.  SEE ALSO        uue(1), uud(1). 

Source: Brendan Eich, the creator of JavaScript. https://twitter.com/BrendanEich/status/998618208725684224