Slack Incoming Webhooks

The @slack/webhook package contains a helper for making requests to Slack's Incoming Webhooks. Use it in your app to send a notification to a channel.

Requirements

This package supports Node v18 and higher. It's highly recommended to use the latest LTS version of node, and the documentation is written using syntax and features from that version.

Installation

$ npm install @slack/webhook

Usage

Initialize the webhook

The package exports an IncomingWebhook class. You'll need to initialize it with the URL you received from Slack. To create a webhook URL, follow the instructions in the Getting started with Incoming Webhooks guide.

const { IncomingWebhook } = require('@slack/webhook');

// Read a url from the environment variables
const url = process.env.SLACK_WEBHOOK_URL;

// Initialize
const webhook = new IncomingWebhook(url);

The webhook can be initialized with default arguments that are reused each time a notification is sent. Use the second parameter to the constructor to set the default arguments.

const { IncomingWebhook } = require('@slack/webhook');
const url = process.env.SLACK_WEBHOOK_URL;

// Initialize with defaults
const webhook = new IncomingWebhook(url, {
  icon_emoji: ':bowtie:',
});

Send a notification

Something interesting just happened in your app, so it's time to send the notification! Just call the .send(options) method on the webhook. The options parameter is an object that should describe the contents of the message. The method returns a Promise that resolves once the notification is sent.

const { IncomingWebhook } = require('@slack/webhook');
const url = process.env.SLACK_WEBHOOK_URL;

const webhook = new IncomingWebhook(url);

// Send the notification
(async () => {
  await webhook.send({
    text: 'I\'ve got news for you...',
  });
})();

Proxy requests with a custom agent

The webhook allows you to customize the HTTP Agent used to create the connection to Slack. Using this option is the best way to make all requests from your app go through a proxy, which is a common requirement in many corporate settings.

In order to create an Agent from some proxy information (such as a host, port, username, and password), you can use one of many npm packages. We recommend https-proxy-agent. Start by installing this package and saving it to your package.json.

$ npm install https-proxy-agent

Import the HttpsProxyAgent class, and create an instance that can be used as the agent option of the IncomingWebhook.

const { IncomingWebhook } = require('@slack/webhook');
const { HttpsProxyAgent } = require('https-proxy-agent');
const url = process.env.SLACK_WEBHOOK_URL;

// One of the ways you can configure HttpsProxyAgent is using a simple string.
// See: https://github.com/TooTallNate/node-https-proxy-agent for more options
const proxy = new HttpsProxyAgent(process.env.http_proxy || 'http://168.63.76.32:3128');

// Initialize with the proxy agent option
const webhook = new IncomingWebhook(token, { agent: proxy });

// Sending this webhook will now go through the proxy
(async () => {
  await webhook.send({
    text: 'I\'ve got news for you...',
  });
})();