Book Image

JavaScript from Frontend to Backend

By : Eric Sarrion
Book Image

JavaScript from Frontend to Backend

By: Eric Sarrion

Overview of this book

JavaScript, the most widely used programming language in the world, has numerous libraries and modules and a dizzying array of need-to-know topics. Picking a starting point can be difficult. Enter JavaScript from Frontend to Backend. This concise, practical guide will get you up to speed in next to no time. This book begins with the basics of variables and objects in JavaScript and then moves quickly on to building components on the client-side with Vue.js and a simple list management application. After that, the focus shifts to the server-side and Node.js, where you’ll examine the MVC model and explore the Express module. Once you've got to grips with the server-side and the client-side, the only thing that remains is the database. You’ll discover MongoDB and the Mongoose module. In the final chapter of this fast-paced guide, you'll combine all these pieces to integrate a Vue.js application into a Node.js server, using Express to structure the server code and MongoDB to store the information. By the end of this book, you will have the skills and confidence to successfully implement JavaScript concepts in your own projects and begin your career as a JavaScript developer.
Table of Contents (14 chapters)
1
Part 1: JavaScript Syntax
4
Part 2: JavaScript on the Client-Side
8
Part 3: JavaScript on the Server-Side

Using promises

Promises are another way to use callback functions. Rather than integrating the callback function into the method call (as a parameter), we use it as a parameter of the new then(callback) method. This simplifies the reading of JavaScript code in case it uses callback functions.

For an object to use the then(callback) method, it must be a Promise class object. The Promise class is a class defined in JavaScript language.

The Promise Class

A Promise class object uses a callback function of the form callback(resolve, reject) as a parameter of its constructor.

The resolve and reject parameters are functions, which will be called from the promise’s callback:

  • When the resolve() function is called, it triggers the then(callback) method.
  • When the reject() function is called, it triggers the catch(callback) method.

The resolve() function must be called, otherwise the then(callback) method cannot be executed. On the other hand, calling the...