72 lines
2.3 KiB
JavaScript
72 lines
2.3 KiB
JavaScript
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/**
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* Feature flag wrapper. Lightweight, dependency-free, env-var driven.
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*
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* Usage:
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* import { isEnabled } from '../../lib/flags';
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* if (isEnabled('bookmark_count_badge', { userId: user?.userId })) {
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* // ...
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* }
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*
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* Flag values resolve from env vars: FLAG_<UPPER_SNAKE_NAME>=on|off|<percent>|<comma list of user ids>
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* Examples:
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* FLAG_BOOKMARK_COUNT_BADGE=on # everyone
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* FLAG_BOOKMARK_COUNT_BADGE=off # nobody
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* FLAG_BOOKMARK_COUNT_BADGE=10 # 10% of users (deterministic per userId)
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* FLAG_BOOKMARK_COUNT_BADGE=u1,u2,u3 # specific user ids
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*
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* For a richer flag system (LaunchDarkly, Statsig, Unleash) replace the
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* resolver below with an SDK call. The public API (isEnabled) stays the same.
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*
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* Pipeline integration: convoys with `skip: flag` in their frontmatter ship
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* without flag-gating. Convoys without `skip: flag` MUST gate the new code
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* behind a flag and document the rollout plan in the convoy file.
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*/
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const KNOWN_FLAGS = new Set([
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// Add flags here as they're created. Helps catch typos.
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// 'bookmark_count_badge',
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]);
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function envName(flag) {
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return `FLAG_${flag.toUpperCase().replace(/[^A-Z0-9]/g, '_')}`;
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}
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function hashUserId(userId, salt) {
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let h = 0;
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const s = `${salt}::${userId}`;
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for (let i = 0; i < s.length; i++) {
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h = (h * 31 + s.charCodeAt(i)) | 0;
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}
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return Math.abs(h) % 100;
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}
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export function isEnabled(flag, ctx = {}) {
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if (process.env.NODE_ENV !== 'test' && !KNOWN_FLAGS.has(flag)) {
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if (typeof console !== 'undefined') {
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console.warn(`[flags] unknown flag '${flag}'. Add it to KNOWN_FLAGS in lib/flags/index.js.`);
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}
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}
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const raw = (ctx.envValue ?? process.env[envName(flag)] ?? 'off').trim().toLowerCase();
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if (raw === 'on' || raw === 'true' || raw === '1') return true;
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if (raw === 'off' || raw === 'false' || raw === '0' || raw === '') return false;
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const pct = Number(raw);
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if (!Number.isNaN(pct) && pct >= 0 && pct <= 100) {
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if (!ctx.userId) return false;
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return hashUserId(String(ctx.userId), flag) < pct;
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}
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if (raw.includes(',') || raw.length > 0) {
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const ids = raw.split(',').map((s) => s.trim()).filter(Boolean);
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return Boolean(ctx.userId && ids.includes(String(ctx.userId)));
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}
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return false;
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}
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export function listKnownFlags() {
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return [...KNOWN_FLAGS].sort();
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}
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