IndexedDB 范围查询与分页游标最佳实践

`title: IndexedDB 范围查询与分页游标最佳实践``categories: Web 开发/前端/数据管理``keywords: IndexedDB,范围查询,IDBKeyRange,游标,分页``description: 使用 IDBKeyRange 与游标实现时间窗与主键范围查询的高效分页，并给出去重与下一页定位策略。`示例async function pageByRange(db, idxName, lower, upper, limit = 50, afterKey) {

return new Promise((resolve, reject) => {

const tx = db.transaction('items', 'readonly');

const idx = tx.objectStore('items').index(idxName);

const range = IDBKeyRange.bound(lower, upper);

const out = []; let count = 0;

idx.openCursor(range, 'next').onsuccess = e => {

const c = e.target.result; if (!c) return resolve({ items: out, nextKey: undefined });

if (afterKey && c.key <= afterKey) { c.continue(afterKey); return; }

out.push(c.value); if (++count >= limit) return resolve({ items: out, nextKey: c.key });

c.continue();

};

tx.onerror = () => reject(tx.error);

});

}