assay.ansi
ANSI SGR → HTML conversion + stripper for log viewers. Pure Lua, no state, no dependencies — safe to call on every log line rendered in a browser.
to_html(line) → string
HTML-escapes &, <, >, ", ' first, then converts SGR (ESC [ ... m) sequences into
<span class="ansi-..."> tags. Recognised codes: 0 reset, 1 bold (ansi-bold), 30..37 /
90..97 foreground (ansi-fg-N), 40..47 / 100..107 background (ansi-bg-N), 39 default fg,
49 default bg. Unknown SGR codes and non-SGR CSI sequences (cursor moves, erase line, …) are
silently dropped. Spans are always closed at reset, default-fg/bg, and end-of-input.
local ansi = require("assay.ansi")
local html = ansi.to_html("\27[32mok\27[0m")
-- html == '<span class="ansi-fg-32">ok</span>'
strip(line) → string
Removes every ANSI CSI sequence (any final byte in 0x40..0x7E, not just m) and returns the
surrounding text byte-for-byte. Does not HTML-escape — the result is plain text, suitable for
non-browser sinks.
local ansi = require("assay.ansi")
local plain = ansi.strip("\27[32mhi\27[0m")
-- plain == "hi"