WP-JSON to RSS proxy

index.mjs

import express from 'express';
import rateLimit from 'express-rate-limit';
import isValidDomain from 'is-valid-domain';
import fetch from 'node-fetch';
import Feed from 'pfeed';

const app = express();
const port = 2847;

/* Rate limiter */
const limiter = rateLimit({
	windowMs: 5 * 60 * 1000, // 5 minutes
	max: 25, // Limit each IP to 25 requests per `window` (here, per 15 minutes)
	standardHeaders: true, // Return rate limit info in the `RateLimit-*` headers
	legacyHeaders: false, // Disable the `X-RateLimit-*` headers
});
//TODO: ENABLE; app.use(limiter);

/* Routes */
app.get('/', (req, res) => {
  res.send('Hi, this is a WP-JSON to RSS proxy, add a domain name to the end of this url to convert its WP-JSON feed (pages & posts) to RSS. Note: subdomains are allowed, but directories are stripped.');
});

// Main function
app.get('/:domain*', (req, res) => {
    try {
        let domain = req.params.domain;
        if(!isValidDomain(domain, {allowUnicode: false})){
            res.send("Domain not valid.");
        }

        let promises = [
            fetch('http://'+domain+'/wp-json/wp/v2/pages?context=embed'),
            fetch('http://'+domain+'/wp-json/wp/v2/posts?scope=embed')
        ];

        let feed = new Feed({
            title: domain,
            id: domain,
            link: domain
        });

        Promise.all(promises).then(rs => {
            Promise.all(rs.map(r => {
                    if(r.status == 200){
                        return r.json()
                    }
            })).then(c => {
                let content = c.flat().filter(i => i !== undefined);
                content.forEach(item => {
                    feed.addItem({
                        title: item.title.rendered,
                        id: item.id,
                        link: item.link,
                        description: item.excerpt.rendered,
                        content: item.excerpt.rendered,
                        date: new Date(item.date)
                    });
                });
                res.set('Content-Type', 'application/rss+xml');
                res.send(feed.rss2());
            }).catch(e => res.send("Something went wrong. The website probably does not support WP-JSON."));;
        }).catch(e => res.send("Something went wrong. The website probably does not support WP-JSON."));
    } catch (error) {
        res.send("Something went wrong. The website probably does not support WP-JSON.");
    }
});

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`);
});

The idea is easy: take any Wordpress based website and convert it to an RSS feed, I know this is possible for posts by using the /feed url in Wordpress, but I came across a website that uses pages for everything and still wanted to follow it. Feel free to use it in whatever way you want, no warranty provided.