I've created a basic APi for my project using node and express. I wanted to add pagination information to the data such as limit, data size, page etc.

I managed to do this but I've got one bug I can't fix. When I load the api in the browser and press refresh it will show me the next set of objects ( as the limit is 10 ), if I press refresh again the results are empty.

{"collectionSize":29,"numOfPages":3,"results":[]}

Is this normal behaviour?

App.js

import express from 'express'
import cors from 'cors'
import indexRouter from './routes/indexRouter.js'

const app = express()
const port = process.env.PORT || 4041

app.use(express.urlencoded({ extended: false }))
app.use(express.json())

app.use(cors()) // <---- use cors middleware

app.use('/', indexRouter)

app.listen(port, () => {
  console.log(`server is running on port: ${port}`)
})

Router.js

import express from 'express';
import projectData from "../mocks/data.js";

const router = express.Router();


const projects = projectData;


router.get("/api/projects", paginate(projects), (req, res) => {
    const { paginatedResult } = res;
    res.json( paginatedResult );
});

const config = {
    startingPage: 1,
    limitDefault: 10,
    modelSize: projects.length,
}

function paginate(model) {
    return async (req, res, next) => {
        const page = parseInt(req.query.page) || config.startingPage;
        const limit = parseInt(req.query.limit) || config.limitDefault;
        const startIndex = (page - 1) * limit;
        const endIndex = page * limit;
        const numOfPages = Math.round(config.modelSize / limit);
        const result = {};

        if (endIndex < model.length) {
            result.next = {
                page: page + 1,
                limit: limit,
            };
        }
        if (startIndex > 0) {
            result.previous = {
                page: page - 1,
                limit: limit,
            };
        }
        try {
            result['collectionSize'] = config.modelSize;
            result['numOfPages'] = numOfPages;
            result.results = model.splice(startIndex, endIndex);
            res.paginatedResult = result;
            return next();
        } catch (e) {
            res.status(500).json({ message: e.message });
        }
    };
}