upload-a-file.js

/**
 * Example for creating and working with the Slack Web API.
 */

/* eslint no-console:0 */
/* eslint vars-on-top:0 */

var fs = require('fs');

var WebClient = require('@slack/client').WebClient;

var token = process.env.SLACK_API_TOKEN || '';
var web = new WebClient(token);

var filePath = '...';
var fileName = 'test_file.csv';

// File upload via content param
var contentOpts = {
  content: fs.readFileSync(filePath)
};

web.files.upload(fileName, contentOpts, function handleContentFileUpload(err, res) {
  console.log(res);
});


// File upload via file param
var streamOpts = {
  file: fs.createReadStream(filePath)
};

web.files.upload(fileName, streamOpts, function handleStreamFileUpload(err, res) {
  console.log(res);
});