Author: John Au-Yeung

To install Yarn in Ubuntu, we add the package repository with Yarn before we install it.

We run

curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list

to add the Yarn package repo.

And then we run

sudo apt-get update && sudo apt-get install yarn

to run apt to install yarn.

To set Node engine to 8.x or 10.x in package.json, we set the engines property.

For instance, in package.json, we write

{
  "engines": {
    "node": "^8 || ^10"
  }
}

to add the engines property into the JSON.

We set the Node engine to 8.x or 10.x with ^8 || ^10.

To fix Webpack: Bundle.js – Uncaught ReferenceError: process is not defined error with JavaScript, we add the process/browser plugin into the Webpack config.

To do this, we write

const webpack = require("webpack");

module.exports = {
  //...
  plugins: [
    new webpack.ProvidePlugin({
      process: "process/browser",
    }),
  ],
};

to add the process/browser plugin with the ProvidePlugin constructor in webpack.config.js.

We also need to require webpack with require.

To disable source maps for React application, we set the GENERATE_SOURCEMAP environment variable to false.

For instance, in package.json, we write

{
  "scripts": {
    "start": "react-scripts start",
    "build": "GENERATE_SOURCEMAP=false react-scripts build",
    "test": "react-scripts test --env=jsdom",
    "eject": "react-scripts eject"
  }
}

to set the GENERATE_SOURCEMAP environment variable to false before running react-scripts build to disable source map generation in the build script.

To get JavaScript Date in UTC with Moment.js, we use the date getTime method.

For instance, we write

const t = new Date().getTime();

to create a new date with the current date and time with the Date constructor.

Then we call getTime to return its timestamp in milliseconds.