Unlocking the Power of Reactivity in Vue.js
Reactivity is at the heart of building modern, interactive user interfaces. In Vue.js, reactivity enables automatic rendering of changes in the application state to the DOM. But have you ever wondered how it works?
What is Reactivity?
Reactivity is a programming paradigm based on data flows and the propagation of change. It allows us to adjust to data changes or events in a declarative manner. In Vue, the reactivity system has been a core feature since its earliest version.
Reactive State in Vue 2
Before we dive into Vue 3, let’s recap how to create reactive data in a Vue 2 application. To keep track of changes, you need to declare the property outside of an object returned from the data function. Vue uses Object.defineProperty() to create getters and setters for each piece of data, ensuring data changes are tracked.
The Limitations of Reactivity in Vue 2
However, Vue 2’s reactivity system has its limitations. By default, JavaScript is not naturally reactive. To add reactivity, we need to turn calculations into functions. But this process can be unreliable and negatively impact performance.
Vue 3: A New Era of Reactivity
In Vue 3, the reactive API has been rewritten to solve many of the shortcomings of Vue 2. The new reactive system utilizes JavaScript’s proxies, which act as wrappers around objects or functions, intercepting operations like getting and setting values. This enables better support for observing changes in data using proxy objects.
How Proxies Work
Proxies enable us to create a proxy for another object, which can intercept and redefine fundamental operations for that object. With proxies, we can intercept operations like get and set and immediately see when data is accessed or changed.
Creating a Proxy
To create a proxy, you need to pass two parameters: target (the data object) and handler (the object that defines the operations you want to intercept). You can then use the Reflect object to reflect the normal object behavior.
The Reactive Method
Vue comes with the reactive method, which creates a reactive state in JavaScript or Vue. The reactive method is a function that creates a proxy and wraps it around provided data objects, turning it into a proxied object. This enables Vue to perform dependency-tracking and change-notification when properties are accessed or modified.
Unlocking the Full Potential of Reactivity
By combining everything we know, we can create our own reactive method that turns our data object into a proxy. This lets us perform change notification on every prop change. The Vue team released the reactivity package as a separate package in Vue 3, which internally tracks all objects that have been made reactive.
The Future of Reactivity
With Vue 3’s reactivity system, every component instance has a corresponding watcher instance, which records any properties “touched” during the component’s render as dependencies. When a dependency’s setter is triggered, it notifies the watcher, causing the component to re-render.
Experience the Power of Reactivity
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