slack file upload axios
const fs = require("fs");
const axios = require("axios");
const FormData = require("form-data");
const form = new FormData();
form.append("token", 'token here');
form.append("channels", channelId);
form.append("file", fs.createReadStream(__dirname + "/aapl.png"), 'file name');
try {
const res = await axios.post("https://slack.com/api/files.upload", form, {
headers: form.getHeaders(),
});
} catch (err) {
throw new Error(err);
}