Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Inside the loop, there is some conditional logic to check if the #first and the #link properties exist, and depending on their values, a different piece of HTML is rendered. Variables are wrapped into curly braces."

A block of code is set as follows:

const toLowerCase = input => { 
  const output = [] 
  for (let i = 0; i < input.length; i++) { 
    output.push(input[i].toLowerCase()) 
  } 
  return output 
}

Any command-line input or output is written as follows:

npm install -g create-react-app

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Let's begin updating the tests, starting with the renders with text ones."