Glossary
abstract interface
A programmatic description of an API that doesn’t include an implementation. In Node.js, a good example is the Streams API.
arrow function
A function written in a shorthand syntax. Instead of writing function () {}, write () => {} when passing functions as arguments to other functions. If the function accepts only one argument, the parentheses can be omitted.
asynchronous
Describes code that doesn’t necessarily run in the order in which it appears. In Node.js, this term is used to distinguish APIs that accept callbacks that will be run at a point in the future. For example, fs.readFile accepts a callback that receives the file’s contents after it has been read.
core modules
The libraries that are built into Node.
destructuring
ECMAScript 2015 introduced destructuring, which allows objects and arrays to be broken into variables and constants. For example, const { name } = { name: 'Alex' } creates a constant called name with the value alex.
ECMAScript standard
ECMAScript is a scripting language specification standardized by Ecma International. There are several ECMAScript standards; this book focuses on ECMAScript 2015 (ECMAScript 6th Edition). JavaScript implementers use the ECMAScript standard to make sure their interpreter is compatible with JavaScript written for other implementations.