Collect channel usernames in Telegram Web (A)

script.js

// Because there is no API method nor programmatic access to Telegram channel usernames,
// this script was created. It is a workaround to collect usernames from the chat folder.
// It collects names and usernames and saves them to an array.
// 1. Open https://web.telegram.org/a/;
// 2. Open the chat filder. Main one is not supported! And there should be no "Archived chats" chat;
// 3. Open the browser console;
// 4. Paste the script and run it;
// 5. Wait for the script to finish. It should take a few minutes.
// Current bugs:
// - The script does not always collect usernames when chat is a forum.

let namesList = [];

let namesListDelta = 1;
let scrollingCounter = 0;
const scrollingCounterLimit = 5;

async function scrollAndCollectNames() {
    while(namesListDelta > 0 || scrollingCounter < scrollingCounterLimit) {
        console.log('Starting a new iteration...');
        let delta = namesList.length;
        let elems = Array.from(document.querySelectorAll("#LeftColumn.Transition .chat-list.Transition_slide-active .ListItem"));
        // elems = elems.slice(0,3); // for testing purposes
        console.log(`Found ${elems.length} elements...`);
        await sleep(200);

        for await (const elem of elems) {
            console.log(`Processing elem with name: ${elem.querySelector(".info .info-row .title")?.innerText}...`);
            const name = elem.querySelector(".info .info-row .title")?.innerText;
            // setting username here is valid, yet it is costly in terms of performance and time
            // so better to do it after filtering names so the loop will not start over again
            // also worth noting that the username is not always available
            // despite teh fact name is not unique, it is still a good enough identifier
            // const username = await getUsername(elem);
            if (!namesList.find(item => item.name === name)) {
                namesList.push({
                    name,
                    username: await getUsername(elem)
                });
            }
        }

        namesListDelta = namesList.length - delta;
        scrollingCounter++;
        console.log(`Scrolling iteration ${scrollingCounter} completed. Names list delta: ${namesListDelta}`);
        // two scroll methods: prefer 1st one
        elems[elems.length-1]?.scrollIntoView();
        // const chatList = document.querySelector(".chat-list.custom-scroll.Transition_slide.Transition_slide-active");
        // chatList.scrollTo(0,9999);
        await new Promise(resolve => setTimeout(resolve, 500));
    }
}

async function getUsername(elem) {
    async function simulateMouseClick(element){
        console.log('Simulating mouse click...');
        const mouseClickEvents = ['mousedown', 'click', 'mouseup'];
        mouseClickEvents.forEach(mouseEventType =>
            element.dispatchEvent(
            new MouseEvent(mouseEventType, {
                view: window,
                bubbles: true,
                cancelable: true,
                buttons: 1
            })
            )
        );
    }

    async function getUserNameText() {
        console.log('Getting username...');
        const rightPane = document.querySelector("#RightColumn");
        const username = rightPane?.querySelector(".ChatExtra .ListItem:nth-child(2) .multiline-item .title")?.innerText || '<no username>';
        return username;
    }

    console.log('Getting username for an element...', elem);
    await simulateMouseClick(elem.querySelector(".ListItem-button"));
    await sleep(2000); // wait for the click event to be processed
    await simulateMouseClick(document.querySelector("#MiddleColumn .MiddleHeader .Transition .chat-info-wrapper"));
    await sleep(2000); // wait for the click event to be processed

    return await getUserNameText();
}


await scrollAndCollectNames().then(() => {
    console.log('Finished collecting names.');
    console.dir(namesList);
}).catch((e) => {
    console.log('Finished collecting names.');
    console.dir(namesList);
});


/**
 *
 * @param {number} ms
 * @returns Promise
 */
function sleep(ms) {
    return new Promise((r) => setTimeout(r, ms));
}