Author: John Au-Yeung

To download and unzip a zip file in memory in Node, we use the adm-zip module.

To install it, we run

npm install adm-zip

Then we write

const fileUrl =
  "https://github.com/mihaifm/linq/releases/download/3.1.1/linq.js-3.1.1.zip";

const AdmZip = require("adm-zip");
const request = require("request");

request.get({ url: fileUrl, encoding: null }, (err, res, body) => {
  const zip = new AdmZip(body);
  const zipEntries = zip.getEntries();
  console.log(zipEntries.length);

  zipEntries.forEach((entry) => {
    if (entry.entryName.match(/readme/i)) console.log(zip.readAsText(entry));
  });
});

to call request.get with an object with the url of the file to unzip.

We get the zip file’s content from body.

And then we call getEntries to get the items in the zip file.

To stream files in Node Express to client, we create a read stream and pipe it.

For instance, we write

app.use((req, res, next) => {
  if (req.url === "somethingorAnother") {
    res.setHeader("content-type", "some/type");
    fs.createReadStream("./toSomeFile").pipe(res);
  } else {
    next();
  }
});

to call createReadStream to create a read stream to read toSomeFile.

And we call pipe with res to pipe the read stream as the response.

To fix Module not found: Can’t resolve ‘fs’ in Next.js application with JavaScript, we set the fs option to false.

For instance, we write

module.exports = {
  webpack5: true,
  webpack: (config) => {
    config.resolve.fallback = { fs: false };

    return config;
  },
};

in webpack.config.js to set fs to false to disable the use of the fs module in the browser environment.

To pass variable to html template in Nodemailer, we put them in the context property.

For instance, we write

const mailOptions = {
  from: "abc@gmail.com",
  to: "username@gmail.com",
  subject: "Sending email",
  template: "yourTemplate",
  context: {
    username,
    whatever: variable,
  },
};

const info = await transporter.sendMail(mailOptions);

to call sendMail with mailOptions to send the email message.

We set the context property to an object with the template variables to interpolate them in the template.

To remove a key with Node redis, we call the del method.

For instance, we write

redis.del('SampleKey');

to remove the entry with key 'SampleKey‘ from Redis with del.