rec-app1.js

app.get("/get-next", (req, res) => {
    let pg_start = Number(req.query.pg_end)
    let pg_end = Number(pg_start) + 12
    res.render("index", {
        books: books.slice(pg_start, pg_end),
        pg_start: pg_start,
        pg_end: pg_end
    })
});


app.get("/get-prev", (req, res) => {
    let pg_end = Number(req.query.pg_start)
    let pg_start = Number(pg_end) - 12

    if (pg_start <= 0) {
        res.render("index", { books: books.slice(0, 12), pg_start: 0, pg_end: 12 })

    } else {
        res.render("index", {
            books: books.slice(pg_start, pg_end),
            pg_start: pg_start,
            pg_end: pg_end
        })

    }
});