server.js

require("dotenv").config()
const express = require("express")
const path = require("path")
const sgMail = require("@sendgrid/mail")

sgMail.setApiKey(process.env.SENDGRID_API_KEY)
const app = express()

if (
  !process.env.TEST_EMAIL_TO_ADDRESS ||
  !process.env.TEST_EMAIL_FROM_ADDRESS ||
  !process.env.SENDGRID_API_KEY ||
  !process.env.TEST_ENDPOINT
) {
  console.log(
    "Make sure to set the following environment variables for your application:\n‣ TEST_EMAIL_TO_ADDRESS\n‣ TEST_EMAIL_FROM_ADDRESS\n‣ SENDGRID_API_KEY\n‣ TEST_ENDPOINT\n",
  )
  process.exit()
}

app.get("/", async (req, res) => {
  res.sendFile(path.join(__dirname, "/index.html"))
})

app.get(`/${process.env.TEST_ENDPOINT}`, async (req, res) => {
  const msg = {
    to: process.env.TEST_EMAIL_TO_ADDRESS,
    from: process.env.TEST_EMAIL_FROM_ADDRESS,
    subject: "My Test Email",
    text: "This is a test email sent by your Node.js application when you visited the test endpoint",
    html: "This is a <strong>test</strong> email sent by your Node.js application when you visited the test endpoint",
  }

  try {
    await sgMail.send(msg)
  } catch (error) {
    console.error(error)

    if (error.response) {
      console.error(error.response.body)
    }
  }

  res.send("Email sent")
})

app.listen(process.env.PORT, () => {
  console.log(`Hello World Application is running on port ${process.env.PORT}`)
})