Mastering JavaScript Functional Programming - Second Edition

Questions

11.1. Decorating methods, the future way: In Chapter 6, Producing Functions – Higher-Order Functions, we wrote a decorator to enable logging for any function. Currently, method decorators are being considered for upcoming versions of JavaScript: refer to https://tc39.github.io/proposal-decorators/ for that (Draft 2 means that inclusion of this feature in the standard is likely, although there may be some additions or small changes). Study the following draft and take a look at what makes the next code tick:

const logging = (target, name, descriptor) => {  const savedMethod = descriptor.value;  descriptor.value = function(...args) {    console.log(`entering ${name}: ${args}`);    try { const valueToReturn = savedMethod.bind(this)(...args); ...