Library: @ananga-ai/funscript

@ananga-ai/funscript reads, checks and repairs .funscript files. It has no dependencies and runs anywhere JavaScript runs. It is the same code as the checker on ananga.ai. MIT licence.

import { parse, check, makeSafe, stringify, axisFromFilename } from '@ananga-ai/funscript';

const result = parse(await file.text());
if (!result.ok) throw new Error(result.error);

const report = check(result.script);            // default limits: 500 units/s, 80 ms
console.log(report.level, report.peakSpeed, report.issues);

const safe = makeSafe(result.script.actions);   // same timing, no move too fast, no gap too short
const text = stringify({ ...result.script, actions: safe });

axisFromFilename('evening.twist.funscript');     // 'R0'

npm install @ananga-ai/funscript

Reference

Function	Returns	What it does
parse(textOrValue)	{ ok: true, script } or { ok: false, error }	Parses JSON text or a value; accepts a byte-order mark
check(script, limits?)	Report	Points, start and end, strokes, average and peak speed, and every problem with a plain-language message
normalize(actions)	Action[]	Valid points only, sorted, clipped to 0–100, one point per time
invert(actions)	Action[]	0 becomes 100
offset(actions, ms)	Action[]	Moves every point in time; points before 0 are dropped
mergeClose(actions, minGap = 80)	Action[]	Merges points closer than minGap ms, keeping the extremes
capSpeed(actions, maxSpeed = 500)	Action[]	Shortens moves that are too fast without changing timing
makeSafe(actions, limits?)	Action[]	normalize, then mergeClose, then capSpeed
stringify(script)	string	One action per line, the layout editors use
positionAt(actions, ms)	number or null	Position at any time, by straight-line interpolation
axisFromFilename(name)	'L0'…'A2'	evening.twist.funscript → R0; plain names → L0
stemFromFilename(name)	string	The media name a script pairs with

The report

check() never throws. Its level is ok, warning or error, and each issue has a code, a severity, a count, up to five example indexes and a message you can show as is.

Code	Severity	Meaning
no-actions	error	Nothing to play
bad-point	warning, or error above 5% of points	A point lacks a number for at or pos
negative-time	warning	A point falls before the media starts
out-of-range	warning	A position is outside 0–100
unsorted	warning	Points are out of time order
duplicate-time	warning	Two points share a time
too-fast	warning	A move is faster than maxSpeed
too-close	warning	A point comes less than minGap ms after the previous one
inverted	warning	The script is marked inverted
partial-range	info	range is set below 100
long-pause	info	The device holds still for more than 10 s