Category: JavaScript

To end a session in Express.js and Node.js, we call the req.session.destroy method.

For instance, we write

req.session.destroy();

to call req.session.destro to end a session with Express.

To fix MongoError: connect ECONNREFUSED 127.0.0.1:27017 error in Node.js, we should check that the connection string is correct.

For instance, we write

const uri = "mongodb://0.0.0.0:27017/";
const client = new MongoClient(uri);

to call MongoClient with the uri connection string to make the connection to MongoDB.

To fill an input field using Puppeteer and JavaScript, we call the page.evaluate method.

For instance, we write

await page.evaluate(() => {
  const email = document.querySelector("#email");
  email.value = "test@example.com";
});

to call page.evaluate with a callback that gets the input with querySelector.

And we set its value to the input value.

To get data out of a Node.js http get request, we listen for the data event.

For instance, we write

require("http").get("http://httpbin.org/ip", (res) => {
  res.setEncoding("utf8");
  res.on("data", (body) => {
    console.log(body);
  });
});

to call res.on to listebn to the data event.

We get the response body from the body parameter in the callback.

To make a https post in Node.js without any third party module, we use fetch.

For instance, we write

const res = await fetch("https://nodejs.org/api/documentation.json");
if (res.ok) {
  const data = await res.json();
  console.log(data);
}

to call fetch to make a get request to the URL.

We get the JSON response with res.json.

We check if the request works with res.ok.

fetch is built into Node.js since version 18.