api-pagination

name	api-pagination
description	Implements efficient API pagination using offset, cursor, and keyset strategies for large datasets. Use when building paginated endpoints, implementing infinite scroll, or optimizing database queries for collections.
license	MIT

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