Subchapter 15.21

Tokens

const q

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Number: 15.21
Position: 21 of 26
Type: JavaScript
Size: 10 KB
Lines: 211

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scripts/lib/tokens.mjs

JavaScript211 lines10 KB

1// tokens.mjs — shared brand-token parsing + semantic role mapping for frame.md /
2// FRAME.md. Used by build-frame.mjs (remix a preset onto brand tokens) and
3// captions.mjs (derive caption colors from frame.md). One mapping → frames and
4// captions stay consistent. Pure node.
5
6// Collect `key: value` pairs under the top-level `colors:` block (until dedent).
7export function parseColors(md) {
8  const out = [];
9  let inBlock = false;
10  for (const line

tokens.mjs on GitHub

of

md.

split

(

/

\r

?

\n

/

)) {

if (/^colors:\s*$/.test(line)) {

inBlock = true;

continue;

}

if (!inBlock) continue;

if (/^\S/.test(line)) break; // dedent to a top-level key → end of block

const m = line.match(

/^\s+([\w-]+):\s*(?:"([^"]+)"|'([^']+)'|(#[0-9a-fA-F]{3,8}|rgba?$[^)]*$|[^#\s][^#\n]*?))\s*(?:#.*)?$/,

);

if (m) out.push([m[1], (m[2] ?? m[3] ?? m[4]).trim()]);

}

return out;

}

// relative luminance of a #rrggbb (null for non-hex like rgba()).

export function lum(v) {

const m = /^#?([0-9a-fA-F]{6})$/.exec(String(v).trim());

if (!m) return null;

const n = parseInt(m[1], 16);

return 0.2126 * ((n >> 16) & 255) + 0.7152 * ((n >> 8) & 255) + 0.0722 * (n & 255);

}

// chroma (max−min channel) of a #rrggbb — a cheap "how colorful" proxy; −1 for non-hex.

export function chroma(v) {

const m = /^#?([0-9a-fA-F]{6})$/.exec(String(v).trim());

if (!m) return -1;

const n = parseInt(m[1], 16);

const r = (n >> 16) & 255,

g = (n >> 8) & 255,

b = n & 255;

return Math.max(r, g, b) - Math.min(r, g, b);

}

// Browser user-agent default colors for links / visited links. These leak into a

// capture from any UNSTYLED <a> and are NOT brand colors — but being pure & saturated

// they beat a real accent on chroma alone. Never let one become the accent.

export const UA_DEFAULT_COLORS = new Set(

["#0000EE", "#0000FF", "#0000CC", "#1A0DAB", "#551A8B", "#EE0000"].map((c) => c.toUpperCase()),

);

// Semantic STATUS roles (green "positive", red "negative"/"error", amber "warning" …). Their HUE

// carries the meaning, so they are never a brand ACCENT — a status red is frequently the most

// chromatic color in a palette (e.g. #dc2626 chroma 182 beats a deep-blue accent #1E40AF chroma

// 145) and would otherwise win a pure chroma ranking, painting captions/highlights the error red.

// build-frame.mjs uses this same key set to protect status colors during the preset→brand remix.

export const STATUS_ROLE_KEY =

// Pick the brand ACCENT — never by raw chroma alone, never a UA-default link color.

// Priority:

// 1) with capture colorStats → the colorful color that RECURS across the UI. The brand

// accent shows up in MANY roles (link text + icon + button + badge), whereas a one-off

// CTA fill appears in just one. So rank chromatic (chroma>40) candidates by role

// diversity first, then total prevalence, then interactive use, then chroma. This keeps

// a pervasive brand color (e.g. an indigo used everywhere) ahead of a single bright

// button fill (e.g. a lime used once) — the old "top interactiveBg" rule picked the

// latter. Requiring interactiveBg>0 is dropped so a text/icon-only accent can still win.

// 2) no stats → most chromatic color AFTER removing UA defaults + `exclude`.

// A stray default link color (e.g. #0000EE) can win under neither path.

export function pickAccent(stats, colors, exclude = []) {

const ban = new Set([...exclude, ...UA_DEFAULT_COLORS].map((c) => String(c).toUpperCase()));

const ok = (h) => /^#[0-9a-fA-F]{6}$/.test(String(h)) && !ban.has(String(h).toUpperCase());

// Prominence rank from the (frequency-ordered) `colors` palette: index 0 = most used.

// A saturated color sitting at the TAIL is almost always a one-off (a single CTA fill),

// not the brand accent — capture colorStats counts are too sparse to tell these apart

// (e.g. Linear's indigo and a lime CTA both register count≈1), but palette ORDER does.

const rank = new Map((colors ?? []).map((h, i) => [String(h).toUpperCase(), i]));

const prom = (h) => (rank.has(String(h).toUpperCase()) ? rank.get(String(h).toUpperCase()) : 1e9);

if (Array.isArray(stats) && stats.length) {

const roles = (s) =>

((s.interactiveBg || 0) > 0 ? 1 : 0) +

((s.textCount || 0) > 0 ? 1 : 0) +

((s.bgCount || 0) > 0 ? 1 : 0);

const a = stats

.filter((s) => ok(s?.hex) && chroma(s.hex) > 40)

.sort(

(x, y) =>

roles(y) - roles(x) || // used in MORE roles (link+icon+button) = the brand accent

prom(x.hex) - prom(y.hex) || // earlier in the palette = more prominent

(y.count || 0) - (x.count || 0) ||

(y.interactiveBg || 0) - (x.interactiveBg || 0) ||

chroma(y.hex) - chroma(x.hex),

);

if (a.length) return a[0].hex;

}

const c = (colors ?? [])

.map(String)

.filter(ok)

.sort((x, y) => chroma(y) - chroma(x));

return c[0];

}

// Derive brand roles from rich capture colorStats (areaBg / interactiveBg / textCount /

// maxArea) — by semantic FUNCTION, not luminance/chroma proxies. Returns null when stats

// are unusable, so the caller can fall back. canvas = the color painting the most real

// background area (the page ground, dark or light); ink = the dominant text color that

// actually contrasts with the canvas; accent via pickAccent.

export function brandRolesFromStats(stats, colorsInOrder) {

if (!Array.isArray(stats) || !stats.length) return null;

const v = stats.filter((s) => /^#[0-9a-fA-F]{6}$/.test(s?.hex || ""));

if (!v.length) return null;

const canvas = [...v].sort(

(a, b) =>

(b.areaBg || 0) - (a.areaBg || 0) ||

(b.maxArea || 0) - (a.maxArea || 0) ||

(b.bgCount || 0) - (a.bgCount || 0),

)[0]?.hex;

// pass the frequency-ordered palette (tokens.colors) so pickAccent can use palette

// PROMINENCE — colorStats counts alone are too sparse to rank rare accents.

const accent = pickAccent(v, colorsInOrder ?? v.map((s) => s.hex), [canvas]);

if (!canvas || !accent) return null;

const cl = lum(canvas) ?? 0;

const ink =

[...v]

.filter((s) => s.hex !== canvas && s.hex !== accent)

.sort((a, b) => (b.textCount || 0) - (a.textCount || 0))

.find((s) => Math.abs((lum(s.hex) ?? 0) - cl) > 64)?.hex ??

(cl > 128 ? "#000000" : "#FFFFFF");

const accent2 =

pickAccent(v, colorsInOrder ?? v.map((s) => s.hex), [canvas, ink, accent]) ?? accent;

return { ink, canvas, accent, accent2 };

}

// Map a list of [key, value] colors to semantic roles. ink = a dark/ink-named

// color (else darkest); canvas = a paper/cream/white-named color (else lightest);

// accents = whatever's left, ranked by chroma (the loudest color is almost always

// the brand accent) — UA-default link colors AND semantic status colors (positive/

// negative/error…) excluded so neither a stray <a> color nor a status red ever wins.

// For an unkeyed brand list, pass synthetic keys — name matching simply no-ops and it

// falls back to luminance/chroma, which is what we want. NOTE: when capture colorStats

// exist, prefer brandRolesFromStats() — it picks by function, not these proxies.

export function semanticColors(colors) {

if (!colors.length) return {};

const named = (re) => colors.find(([k]) => re.test(k));

const hexes = colors.filter(([, v]) => lum(v) != null);

const byLum = [...hexes].sort((a, b) => (lum(a[1]) ?? 1e9) - (lum(b[1]) ?? 1e9));

const pick = (m, fallback) => (m ? m[1] : fallback ? fallback[1] : undefined);

// "ink" must be a whole word-segment so "soft-pink"/"pink" don't match it.

const ink = pick(

byLum[0] ?? colors[0],

);

const canvas = pick(

byLum[byLum.length - 1] ?? colors[colors.length - 1],

);

const accents = colors

.filter(

([k, v]) =>

v !== ink &&

v !== canvas &&

!UA_DEFAULT_COLORS.has(String(v).toUpperCase()) &&

!STATUS_ROLE_KEY.test(k), // a status red/green carries meaning by hue — never an accent

)

.sort((a, b) => chroma(b[1]) - chroma(a[1]))

.map(([, v]) => v);

return { ink, canvas, accent: accents[0] ?? ink, accent2: accents[1] ?? accents[0] ?? ink };

}

// Collect role→fontFamily under the top-level `typography:` block; pick a display

// + body family from the usual role names. Returns quoted families (or null).

export function parseFonts(md) {

const roles = {};

let inBlock = false;

for (const line of md.split(/\r?\n/)) {

if (/^typography:\s*$/.test(line)) {

inBlock = true;

continue;

}

if (!inBlock) continue;

if (/^\S/.test(line)) break;

const m = line.match(/^\s+([\w-]+):\s*\{[^}]*fontFamily:\s*"([^"]+)"/);

if (m) roles[m[1]] = m[2];

}

const q = (s) => (s ? `"${s}"` : null);

const body = roles.body ?? roles.subtitle ?? Object.values(roles)[0];

const display =

roles.display ??

roles.headline ??

roles["card-headline"] ??

roles["section-headline"] ??

roles["quote-display"] ??

roles.h1 ??

roles.h2 ??

roles.title ??

roles.hero ??

body;

// the monospace / chrome family (code, tags, ticks, page numbers) — so the remix can

// route a captured brand mono (Berkeley Mono, JetBrains Mono…) onto this role instead

// of the reading body. null when the preset has no distinct mono role.

const mono =

roles.mono ??

roles["mono-tag"] ??

roles["mono-chrome"] ??

roles["mono-tick"] ??

roles.code ??

roles.data ??

roles.pagenum ??

null;

return { display: q(display), body: q(body), mono: q(mono) };

}