Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Keep in mind that you won't always be needing util.promisify()."

A block of code is set as follows:

// Source file: src/roundmath.js

/* @flow */
"use strict";

// continues..

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

// Source file: src/flowcomments.js

let someFlag /*: boolean */;
let greatTotal /*: number */;
let firstName /*: string */;

function toString(x /*: number */) /*: string */ {
    return String(x);
}

let traffic /*: "red" | "amber" | "green" */;

// continues...

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

> npm install moment --save
> npm run addTypes

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "VSC provides full access to commands through its Command Palette... as seen in the following screenshot."