load rss feed titles with node.js streams

rssTitlesNodejsStreamParser.js

#!/usr/bin/env node
// @ts-check

const https = require('https');
const { finished } = require('stream');

load_rss_feed_titles('https://news.google.com/rss?hl=en-US&gl=US&ceid=US:en')
    .then(console.log).catch(console.error);
load_rss_feed_titles('https://news.google.com/rss?hl=ru&gl=RU&ceid=RU:ru')
    .then(console.log).catch(console.error);


function load_rss_feed_titles(url) {
    const itemRegexp = /(?:(?<=<item>)(.+)(?=<\/item>)|(?<=<item>)(.+))/g;
    const titleRegexp = /<title>(.+?)<\/title>/;

    return new Promise((resolve, reject) => {
        https.get(url, (res) => {
            if (res.statusCode !== 200) {
                reject(new Error(`statusCode=${res.statusCode}`));
            }

            const titles = [];
            let buff;
            res.setEncoding('utf8');
            res.on('data', (d) => {
                res.pause();
    
                buff = buff !== undefined ? buff + d : d;
                const str = buff.toString('utf8');
                const matches = [...str.matchAll(itemRegexp)];
                if (matches.length > 0) {
                    buff = undefined;
                    for (const [x, full_item, part_item] of matches) {
                        if (full_item !== null && full_item !== undefined && full_item !== '') {
                            const title = full_item.match(titleRegexp);
                            if (title) {
                                titles.push(title[1]);
                            }
                        } else if (part_item !== null && part_item !== undefined && part_item !== '') {
                            buff = `<item>${part_item}`;
                        }
                    }
                }
    
                res.resume();
            });
            finished(res, (err) => {
                if (err) {
                    reject(err);
                } else {
                    resolve(titles);
                }
            });
        }).on('error', (err) => {
            reject(err);
        });
    });
}