What is Vue.js?

A quick recap about Vue.js

Let's get straight to the point.
But before that, let's quickly recap what Vue.js is all about.

What's Vue.js again?

Vue.js is a "friendly, high-performance, and versatile framework for building web user interfaces."
This is stated on the official documentation's homepage.
For this, I believe it's clearer to directly quote the official words without adding my own interpretation, so I've cited them below:

Vue (pronounced /vjuː/, like view) is a JavaScript framework for building user interfaces. It builds on top of standard HTML, CSS, and JavaScript and provides a declarative and component-based programming model that helps you efficiently develop user interfaces, be they simple or complex.

Declarative Rendering: Vue extends standard HTML with a template syntax that allows us to declaratively describe HTML output based on JavaScript state.

Reactivity: Vue automatically tracks JavaScript state changes and efficiently updates the DOM when changes happen.

Here's a minimal example:

import { createApp } from 'vue'

createApp({
  data() {
    return {
      count: 0,
    }
  },
}).mount('#app')

<div id="app">
  <button @click="count++">Count is: {{ count }}</button>
</div>

reference source

For declarative rendering and reactivity, we will delve into them in detail in their respective chapters, so a high-level understanding is fine for now.

Also, the term "framework" has come up here, and Vue.js promotes itself as a "progressive framework." For more on that, I believe it's best to refer directly to the following section of the documentation:

https://vuejs.org/guide/introduction.html#the-progressive-framework

The difference between the official documentation and this book

The official documentation focuses on "how to use Vue.js," with an abundance of tutorials and guides provided.

However, this book takes a slightly different approach, focusing on "how Vue.js is implemented." We'll write actual code to create a mini version of Vue.js.

Also, this book isn't an official publication and may not be exhaustive. There might be some errors or omissions, so I'd appreciate any feedback or corrections.