Delete Slack Messages

__readme.md

This script (probably) deletes all your Slack messages, for all channels in a given Slack Workspace. It is intended to be run from the Chrome Devtools console.

Usage

1. Get an API token for a given workspace from: https://api.slack.com/legacy/custom-integrations/legacy-tokens
2. Replace the API token on line 1 with the one you received from the page in step 1.
3. Navigate to the web client for your Slack Workspace.
4. Paste the whole thing into your Chrome Devtools console and execute it.
5. You'll now have an async function called fuckMeUpFam in the global scope. Invoke it, passing in your Slack display name. E.g. if you get @-replied as "Jeff Gravy", you would invoke await fuckMeUpFam("Jeff Gravy") in the console.

wham.js

const apiToken = "Not bothering with OAuth dance for this script, just get a legacy token here: https://api.slack.com/legacy/custom-integrations/legacy-tokens";
const commonRequestHeaders = {
   Authorization: `Bearer ${apiToken}`
};

const resources = {
  conversationList: 'conversations.list',
  usersList: 'users.list',
  conversationsHistory: 'conversations.history',
  chatDelete: 'chat.delete'
}

async function getChannels() {
  const pages = await exhaustPagination(resources.conversationList);
  const channels = pages.reduce((channels, nextPage) => channels.concat(nextPage.channels), []);
  return channels;
}

async function getMe(mySlackName){
  const pages = await exhaustPagination(resources.usersList);
  const users = pages.reduce((users, nextPage) => users.concat(nextPage.members), []);
  const matches = users.filter((user) => user.real_name === mySlackName);
  if (matches.length < 1) {
    console.warn(`${mySlackName} was not found.`);
  }
  return matches[0];
}

async function getAllMessages(channelId){
  const pages = await exhaustPagination(resources.conversationsHistory, {channel: channelId});
  const messages = pages.reduce((messages, nextPage) => messages.concat(nextPage.messages), []);
  return messages;
}

async function deleteMessage(channelId, message){
  const url = `https://app.slack.com/api/${resources.chatDelete}?channel=${channelId}&ts=${message.ts}`;
  console.info(`Attempting to delete message: "${message.text}"`);
  const response = await fetch(url, {
    headers: commonRequestHeaders,
    method: 'POST'
  });
  const responseBody = await response.json();
  if (responseBody.ok !== true){
    console.error("Message delete attempted for message:", message);
    console.error(`Received non-"ok" response fetching ${url}`);
    console.error(responseBody);
  }
}

async function exhaustPagination(resource, queryParams){
  const pages = [];
  async function getNextPage(cursor){
    let url = `https://app.slack.com/api/${resource}?limit=999${cursor ? "&cursor=" + cursor : ""}`;
    if (queryParams){
      for (let [key, value] of Object.entries(queryParams)) {
       url = `${url}&${key}=${value}`
      }
    }

    const response = await fetch(url, {
      headers: commonRequestHeaders
    });
    const responseBody = await response.json();
    if (responseBody.ok !== true){
      console.error(`Received non-"ok" response fetching ${url}`);
      console.error(responseBody);
    } else {
      pages.push(responseBody)
      if (responseBody.response_metadata && responseBody.response_metadata.next_cursor !== "") {
        await getNextPage(responseBody.response_metadata.next_cursor);
      }
    }
  }
  await getNextPage();
  console.log(`All pages for ${resource}:`, queryParams)
  console.log(pages);

  return pages;
}

async function fuckMeUpFam(mySlackName){
  const channels = await getChannels();

  // uncomment for a dry run against #test-channel
  // const channels = [{id: "C011DKXANH3", name: "test-channel", is_channel: true, is_group: false, is_im: false}]

  const channelIds = channels.map(c => c.id);
  for (let i = 0; i < channelIds.length; i++) {
    const channelId = channelIds[i];
    const me = await getMe(mySlackName);
    const messages = await getAllMessages(channelId);
    const myMessages = messages.filter(m => m.user === me.id);
    for (let j = 0; j < myMessages.length; j++) {
      await deleteMessage(channelId, myMessages[j]);
    }
  }
}