simple and useful example of API pagination implementation

api-pagination.js

// assume that you develop a course's API GET endpoint
// best practices is pagination of /v1/courses endpoint
// if you is receving page & limit paramas as a queries, aditional filter params are optional 

// this is a example of our endpoint with pagination, sorting & filtering 

// we have  a request containing data like params, queries, headers...
const { reviews, status, title, page = 1, limit = 20, sort } = request.query // using object destructuring

let List = [] // get data form database

// filter data by params pased on request
let mockList = List.filter(item => {
    if (reviews && item.reviews !== +reviews) return false
    if (status && item.status !== parseInt(status)) return false
    if (title && item.title.indexOf(title) < 0) return false
    return true
})

// sorting by uuid field
if (sort === '-uuid') {
    mockList = mockList.reverse()
}

// pagination filtered list
const pageList = mockList.filter((item, index) => index < limit * page && index >= limit * (page - 1))

return {
    code: 200, // status code OK!
    data: {
        total: mockList.length, // total database resources
        page, // current page returned
        items: pageList // current array with query matched
    }
}

// this hipotetic example have some considerations
// for example, get all resources of database can provoke memory leak
// has not the best performance with many requests
// is just an example, nowadays depends on what datadabase is using, there are internal 
// libraries to do pagination and have better performance