API Pagination

Implement scalable pagination strategies for handling large datasets efficiently.

Pagination Strategies

Strategy Best For Performance

Offset/Limit Small datasets, simple UI O(n)

Cursor Infinite scroll, real-time O(1)

Keyset Large datasets O(1)

Offset Pagination

app.get('/products', async (req, res) => { const page = parseInt(req.query.page) || 1; const limit = Math.min(parseInt(req.query.limit) || 20, 100); const offset = (page - 1) * limit;

const [products, total] = await Promise.all([ Product.find().skip(offset).limit(limit), Product.countDocuments() ]);

res.json({ data: products, pagination: { page, limit, total, totalPages: Math.ceil(total / limit) } }); });

Cursor Pagination

app.get('/posts', async (req, res) => { const limit = 20; const cursor = req.query.cursor;

const query = cursor ? { _id: { $gt: Buffer.from(cursor, 'base64').toString() } } : {};

const posts = await Post.find(query).limit(limit + 1); const hasMore = posts.length > limit; if (hasMore) posts.pop();

res.json({ data: posts, nextCursor: hasMore ? Buffer.from(posts[posts.length - 1]._id).toString('base64') : null }); });

Response Format

{ "data": [...], "pagination": { "page": 2, "limit": 20, "total": 150, "totalPages": 8 }, "links": { "first": "/api/products?page=1", "prev": "/api/products?page=1", "next": "/api/products?page=3", "last": "/api/products?page=8" } }

Best Practices

• Set reasonable max limits (e.g., 100)

• Use cursor pagination for large datasets

• Index sorting fields

• Avoid COUNT queries when possible

• Never allow unlimited page sizes