Author: John Au-Yeung

Sometimes, we want to get number of processors available with Node.js.

In this article, we’ll look at how to get number of processors available with Node.js.

How to get number of processors available with Node.js?

To get number of processors available with Node.js, we can use the os.cpus method.

For instance, we write

const os = require("os");
const cpuCount = os.cpus().length;

to get the cpuCount with os.cpus().length.

Conclusion

To get number of processors available with Node.js, we can use the os.cpus method.

Sometimes, we want to receive email in Node.js.

In this article, we’ll look at how to receive email in Node.js.

How to receive email in Node.js?

To receive email in Node.js, we can use the node-imap package.

To install it, we run

npm install imap

Then we use it by writing

const Imap = require("imap");
const { inspect } = require("util");

const imap = new Imap({
  user: "mygmailname@gmail.com",
  password: "mygmailpassword",
  host: "imap.gmail.com",
  port: 993,
  tls: true,
});

const openInbox = (cb) => {
  imap.openBox("INBOX", true, cb);
};

imap.once("ready", () => {
  openInbox(function (err, box) {
    if (err) throw err;
    const f = imap.seq.fetch("1:3", {
      bodies: "HEADER.FIELDS (FROM TO SUBJECT DATE)",
      struct: true,
    });
    f.on("message", (msg, seqno) => {
      console.log("Message #%d", seqno);
      const prefix = "(#" + seqno + ") ";
      msg.on("body", (stream, info) => {
        let buffer = "";
        stream.on("data", (chunk) => {
          buffer += chunk.toString("utf8");
        });
        stream.once("end", () => {
          console.log(
            prefix + "Parsed header: %s",
            inspect(Imap.parseHeader(buffer))
          );
        });
      });
      msg.once("attributes", (attrs) => {
        console.log(prefix + "Attributes: %s", inspect(attrs, false, 8));
      });
      msg.once("end", () => {
        console.log(prefix + "Finished");
      });
    });
    f.once("error", (err) => {
      console.log("Fetch error: " + err);
    });
    f.once("end", () => {
      console.log("Done fetching all messages!");
      imap.end();
    });
  });
});

imap.once("error", (err) => {
  console.log(err);
});

imap.once("end", () => {
  console.log("Connection ended");
});

imap.connect();

to receive email via IMAP.

We create an IMAP instance with the credentials for the email server.

Then we listen to the ready event with imap.onace.

In it, we call imap.seq.fetch to fetch the emails.

And then we call f.on with 'message' and the callback that gets the messages from a stream.

We received everything when the end event is received, which we listen to by calling msg.once with 'end' and the event handler callback.

And we call imap.connect() to make the connection to the IMAP server.

Conclusion

To receive email in Node.js, we can use the node-imap package.

To fix the ‘Error: Cannot GET /’ error message with Node.js and Express, we need to add the route handler for the GET / route.

For instance, we write

app.get("/", (req, res) => {
  res.render("index.html");
});

to call app.get with '/' and the route handler to handle GET requests to the / route.

In the route handler for the GET / route, we call res.render to render the index.html template on the screen.