gyazo.com const buildBiyon = (max) => { let incr = 1; let count = 0; return () => { if (count === 1) { incr = 1; } if (count >= max) { incr = -1; } count = count + incr; return "ニ".repeat(count); }; }; (() => { const biyon = buildBiyon(5)…