Differences between VueJS 2 and VueJS 3

Published on June 20, 2024

Zignuts Technolab

VueJS 2 and VueJS 3
Web Application Development

Basic Introduction of VueJS 2 and VueJS 3

  • In the realm of front-end development, there's a plethora of leading frameworks such as Angular, React, and Vue.js, each offering its own set of advantages for developers crafting robust web applications. Vue.js stands out as a powerhouse, dedicated to sculpting rich and intuitive user interfaces.
  • For newcomers venturing into the world of VueJS, a pressing question often arises: which stable version should one opt for? Vue3 emerges as a stalwart choice, currently dominating the market and embraced globally by countless companies for crafting responsive web applications.
  • The arrival of Vue3 has ignited a wave of curiosity among developers eager to explore the technical advancements introduced in the latest iteration of Vue. Boasting a host of innovative features, Vue3 promises to turbocharge your applications, leveraging cutting-edge concepts to enhance speed and responsiveness.

Key Takeaways

  • Composition API: Vue 3 introduces the Composition API, a paradigm shift from Vue 2's Options API, offering more flexibility and scalability in organizing and reusing code logic.
  • Performance Enhancements: Vue 3 is engineered with performance in mind, featuring a reactivity system rewrite that significantly boosts rendering efficiency, resulting in faster and more responsive applications compared to Vue
  • Tree Shaking and Bundle Size Reduction: With Vue 3's improved module structure and better optimization, developers can leverage tree shaking techniques more effectively, leading to smaller bundle sizes and improved load times compared to Vue 2.
  • Teleport Component: Vue 3 introduces the Teleport component, allowing developers to seamlessly render content at a different location in the DOM hierarchy, enabling smoother transitions and enhanced flexibility in building complex UIs.
  • Composition API vs. Options API: While Vue 2 relies on the Options API for structuring components, Vue 3's Composition API offers a more intuitive and powerful approach for managing component logic, making code organization and reuse more straightforward and efficient.
  • TypeScript Support: Vue 3 provides enhanced support for TypeScript out of the box, making it easier for developers to leverage the benefits of static typing and catch errors during development, which was less robust in Vue 2.
  • Ecosystem Compatibility: While Vue 3 introduces significant improvements, it's essential to consider ecosystem compatibility, as some plugins and libraries may require updates to fully support Vue 3, whereas Vue 2 has a more mature and stable ecosystem.
  • Migration Path: Vue 3 offers a clear migration path for projects built on Vue 2, with tools and documentation provided to facilitate a smooth transition, ensuring that existing Vue applications can benefit from the latest features without major disruptions.
  • Developer Experience: Vue 3 aims to enhance the developer experience with improved tooling, better error handling, and more comprehensive documentation, striving to make the development process smoother and more enjoyable compared to Vue 2.
  • Community and Support: While Vue 3 is gaining momentum, Vue 2 boasts a large and active community with extensive resources and support available, making it a reliable choice for projects requiring stability and long-term maintenance.

History of Vue.JS Framework

To comprehend the disparities between Vue 2 and Vue 3, it's essential to trace the framework's evolution. Vue.js embarked on its journey as a modest runtime library, gradually transitioning into a full-fledged framework over time. Today, Vue.js has earned recognition as an accessible, high-performing, and adaptable framework, pivotal in the development of dynamic web user interfaces.

Definition: Vue.js 2

Vue.js 2 is a prevalent JavaScript framework utilized extensively in crafting user interfaces. Recognized for its simplicity and adaptability, it empowers web developers to construct interactive web applications with ease. Vue.js 2 operates on a reactive and component-based architecture, facilitating the segmentation of the application's UI into reusable components for enhanced modularity and scalability.

Definition: Vue.js 3

Vue.js 3 stands as the latest iteration of the Vue.js JavaScript framework, meticulously crafted for the development of modern and high-performing web applications. Distinguished by a host of significant improvements and optimizations over its predecessor, Vue 2, Vue 3 places emphasis on bolstered performance, reduced bundle sizes, and enhanced TypeScript integration. Central to Vue 3 is the Composition API, offering developers a more adaptable and modular approach to organizing code within components, fostering greater code reusability and maintainability.

Moreover, Vue.js 3 enhances the virtual DOM algorithm to streamline rendering and updates, resulting in expedited application performance and smoother user experiences. Despite the advancements of Vue 3, Vue 2 continues to be utilized by numerous companies worldwide, attributed to its distinct advantages and the relatively recent emergence of Vue 3, with Vue 2 slated to remain supported until the end of 2023.

Differences Between Vue2 and Vue3

Creating An Application

The initial disparity between Vue 2 and Vue 3 arises during the process of creating an application from scratch. To kickstart the standard application setup, including the installation of Vue CLI (Command Line Interface), developers must follow specific procedures.

  • To streamline the installation process, execute the following command to install Vue CLI globally:
  • For Vue 2 installation, input the following command:
  • For the latest version, Vue 3, utilize the command:
  • While the installation steps remain similar, minor syntax distinctions and structural changes differentiate the creation process between Vue2 and Vue3.
  • Below, I present code snippets exemplifying these variances.

Example of main.js file for Vue2 

Example of main.js file for Vue3

Multiple Root

In Vue 2, adhering to a single root element within a template is imperative; any attempt to include multiple roots results in an error being thrown. However, Vue 3 diverges from this restriction, enabling the inclusion of multiple root elements within the same template without encountering errors. This newfound flexibility in Vue 3's templating system provides developers with greater freedom in structuring their components.

In a Vue 2 application, attempting to include multiple root elements within a template will halt the process, triggering an error message. Conversely, in Vue 3, such constraints are lifted, allowing the inclusion of multiple root elements without triggering error messages.

Here's an example showcasing the difference:

This distinction affords developers greater flexibility in Vue 3, as demonstrated by the inclusion of multiple web components within the same file without encountering any error messages.

Example of HelloWorld and AppForm components

And if we run the application, the outcome is

VueJS 2 and VueJS 3

Introducing Fragments in Vue 3

  • Introducing Fragments in Vue 3 marks a significant departure from previous versions. Before delving into method creation in Vue 2 and Vue 3 applications, establishing a template and organizing a coherent data structure for the app is essential.
  • Let's initiate this process by crafting component options within the Vue 2 application. However, it's imperative to note that Vue 3 inherently supports Fragments, allowing components to encompass multiple root nodes.
  • In essence, Fragments in Vue 3 enable the creation of components with more than one root node, a departure from the single-root node constraint in Vue 2. Thus, we can proceed to create a root node for Form components in both the Vue 2 and Vue 3 applications.

Form Component in Vue 2 application

Below are the Form Component implementations in Vue 2 and Vue 3:

Vue 2 Application Form Component:

Vue 3 Application Form Component:

These implementations showcase the Form Component templates for both Vue 2 and Vue 3 applications, illustrating the differences in syntax and data handling between the two versions.

Data Property in Vue 2 vs Vue 3

In Vue 2 and Vue 3, managing data differs due to the Options API in Vue 2 and the Composition API in Vue 3. The Options API organizes code into distinct properties like data, computed properties, and methods, while the Composition API groups code by function.

For a simple form component with properties for employee username and password, let's compare the data setup in Vue 2 and Vue 3.

Vue 2 Code with Options API:

Vue 3 Code with Composition API:

In Vue 3's Composition API, developers leverage the setup() method to handle component initialization. By using reactive() from Vue, data becomes reactive. This approach offers developers finer control over reactivity, improving performance and code organization.

Methods in Vue 2 vs Vue 3

Creating methods in Vue 2 and Vue 3 applications involves different approaches, with Vue 2 relying on the Options API and Vue 3 utilizing the Composition API.

Vue 2 Method Creation:

In Vue 2, methods are declared within the methods property of the component object.

Vue 3 Method Creation:

In Vue 3, the Composition API is used to handle methods. Within the setup() method, methods are declared as regular JavaScript functions, which are then returned for accessibility within other parts of the component. This approach offers more flexibility and control over method declaration compared to Vue 2's Options API.

Lifecycle Hooks

In Vue 2, developers can directly access lifecycle hooks from the component options. For instance:

In Vue 3, with the Composition API, the setup() method includes lifecycle hooks. However, these hooks are not automatically available and need to be imported. For example, to use the mounted lifecycle hook, developers need to import the onMounted() method.

Here's how it's done:

In this example, the onMounted() method is imported, and inside the setup() method, it's utilized to define the behavior when the component is mounted. This approach offers more flexibility and control over lifecycle hooks in Vue 3 compared to Vue 2.

Computed Properties

In Vue 2, computed properties are defined in a separate section, distinct from data properties. Here's an example:

To use computed properties in Vue 3, developers need to import computed into the component. The structure is similar to an arrow function, but it must be wrapped in a computed key within the setup() method:

In this Vue 3 example, computed() from Vue is imported, and the computed property is defined within the setup() method. Finally, it's returned for use in the template. This demonstrates the process of using computed properties in Vue 3, which offers more flexibility and control compared to Vue 2.

Accessing Props

Accessing props differs significantly between Vue 2 and Vue 3, particularly in how props are referenced within components.

In Vue 2, referencing props typically involves using `this` within the component's methods or lifecycle hooks. For instance:

In Vue 3, however, accessing props is handled differently. The setup() method is used, which takes two arguments: props for immutable access to the component's props and context for selected properties exposed by Vue 3 (such as emit, slots, and attrs). Here's how it looks:

For non-<script setup> components:

In Vue 3's single file components (SFCs) using <script setup>, props can be declared using the defineProps() macro:

These approaches demonstrate the difference in accessing props between Vue 2 and Vue 3, showcasing how Vue 3 offers more flexibility and clarity in managing props within components.

Events in Vue 2 vs Vue 3

In Vue 2, emitting events involves using this.$emit within the component's methods to trigger an event that can be caught by a parent component. Here's an example of how it's done:

In Vue 3, accessing this directly is no longer the norm, so emitting events is handled differently. The setup() method provides access to the emit function via the context argument. Here's how it looks:

Additionally, in Vue 3, a component can explicitly declare the events it will emit using the defineEmits() macro within the <script setup> section:

In this example, defineEmits() declares the events the component will emit, and then the emit function can be used to trigger those events. This approach ensures clarity and consistency in event handling within Vue 3 components.

Introducing Portals functionality in Vue 3


Portals in Vue 3 offer a convenient way to render components from one part of the DOM tree into another component in a different part of the DOM tree. While Vue 2 required the use of a third-party plugin like portal-vue to achieve similar functionality, Vue 3 introduced an in-built <Teleport> feature, making portal usage simpler and more accessible.

With Vue 3's <Teleport> tag, any code enclosed within it can be seamlessly teleported to a specified target location. The<Teleport> tag accepts a to attribute specifying the target destination.

Here's a basic example to illustrate the concept of portals:

In this example, any content enclosed within the <Teleport> tag, such as the "Hey, Everyone!!!" message, will be displayed at the target location specified by the to attribute.

At the time of writing, please note that <Teleport> functionality may not be available in certain versions of Vue 3, such as the Alpha version mentioned above. However, once implemented, <Teleport> offers a streamlined approach to managing portal functionality within Vue 3 components.

Filters in Vue 2 vs Vue 3

In Vue 2, developers can define filters to apply common text formatting directly within the template. Here's an example:

In Vue 3, achieving the same functionality involves using computed properties. Here's how it's done:

In this Vue 3 example, a reactive accountBalance variable is defined using ref(), and then a computed property accountInUSD is created to format the balance in USD. While filters are not available in Vue 3, computed properties provide a flexible alternative for achieving similar functionality.

Watch in Vue 2 vs Vue 3

In Vue 2, developers can utilize the watch property to observe and react to data changes. Here's an example:

In Vue 3, developers have the option to use the watchEffect() function for reactive observing changes in data. watchEffect() reruns whenever its dependencies change. This provides flexibility and efficiency in handling reactive updates.

Here's how it's done:

Alternatively, developers can also use the watch function, which is familiar to Vue 2 users:

Both approaches offer reactive data observing capabilities, providing developers with options based on their preferences and familiarity with Vue 2 or Vue 3 syntax.

Event buses in Vue 2 and Vue 3

Event Buses in Vue 2:

In Vue 2, event buses are commonly used for communication between components. Here's how you can implement event buses in Vue 2:

Firstly, you can create a global event bus instance using Vue's prototype:

With the event bus set up, you can emit and listen for events in your components:

Event Buses in Vue 3:

In Vue 3, you can use the Mitt library for handling events between components. Here's how you can set up Mitt in a Vue 3 project:

First, install the Mitt library:

Then, in the main.js file, provide Mitt globally:

Now, you can use Mitt in your Vue 3 components by injecting it:

This setup allows you to achieve similar functionality to event buses in Vue 2, with the added benefits of being compatible with Vue 3's composition API and providing a lightweight solution for event handling.

Router in Vue2 and Vue3

Router in Vue 2:

In Vue.js 2, setting up the router involves creating a router instance separately and passing it to the Vue application using Vue.use(Router) before creating the root Vue instance. Here's an example:

Usage in Vue 2 components involves accessing the router instance through $router:

Router in Vue 3:

In Vue.js 3, router setup is more aligned with the Composition API style. You can create the router instance directly inside your application setup. Here's an example:

Usage in Vue 3 components involves using useRouter and useRoute from vue-router:

With Vue 3, router setup becomes more streamlined and aligns better with the Composition API paradigm.

State Management

State Management in Vue 2 with Vuex:

In Vue.js 2, Vuex is the most commonly used state management library. It provides a centralized store for all the components in an application. Here's how you typically set up and use Vuex in a Vue 2 application:

  1. Install Vuex:
  1. Create a Vuex store:
  1. Use the store in your Vue components:

State Management in Vue 3 with Vuex 4 or Pinia:

In Vue.js 3, Vuex 4 is compatible for state management, but you also have the option of using Pinia, a new state management alternative designed specifically for Vue3.

Here's how you can set up and use Vuex 4 or Pinia in a Vue 3 application:

Using Vuex 4:

  1. Install Vuex 4:
  1. Create a Vuex store (similar to Vue 2 setup):
  1. Use the store in your Vue components (similar to Vue 2 setup).

Using Pinia:

  1. Install Pinia:
  1. Create a Pinia store:
  1. Use the store in your Vue components:

In Vue 3, you have the flexibility to choose between Vuex 4 and Pinia for state management, depending on your project requirements and preferences. Both libraries offer powerful state management solutions tailored for Vue 3 applications.

The Technical, User-facing, and Business-related differences between Vue 2 and Vue 3:

Vue 2 and Vue 3 Technical Differences:

  • Composition APIsome text
    • Vue 3 introduces the Composition API, allowing for more intuitive and efficient organization of component logic.
    • Vue 2 primarily uses the Options API, which separates concerns into different sections of the component.
  • Performancesome text
    • Vue 3 offers significant performance improvements over Vue 2 due to its optimized virtual DOM implementation, better reactivity tracking, and more efficient component updates.
    • Vue 3's compiler generates more efficient render functions, resulting in faster initial renders and updates.
  • Tree Shakingsome text
    • Vue 3's modularized codebase allows for more efficient tree shaking during the build process, resulting in smaller bundle sizes.
    • Vue 2's less modular codebase may lead to larger bundle sizes, especially when using specific features of Vue.
  • Reactivity Systemsome text
    • Vue 3 utilizes ES6 Proxies for reactivity, providing more granular reactivity tracking and better performance compared to Vue 2's getter/setter-based system.

Vue 2 and Vue 3 User-Facing Differences:

  • Development Experiencesome text
    • Vue 3 offers a streamlined development experience with faster component re-renders during development and improved code organization using the Composition API.
    • Vue 2 may require more manual optimization and organization of code.
  • Tooling Supportsome text
    • While Vue 3 initially had limited tooling support, the ecosystem has matured over time with updated libraries, plugins, and extensions to support the latest version.
    • Vue CLI, Vue Devtools, and other essential tooling now fully support Vue 3 development.

Vue 2 and Vue 3 Business Side Differences:

  • Migration Costssome text
    • Migrating from Vue 2 to Vue 3 may involve significant costs for large codebases due to potential syntax changes and refactoring to leverage new features like the Composition API.
  • Long-Term Supportsome text
    • Vue 2 is expected to have less or no support for future features, while Vue 3 offers ongoing improvements, support, and features.
  • Community Adoptionsome text
    • Businesses need to consider the adoption rate of Vue 3 within the developer community when making technology stack choices and investing in training and hiring developers.

Higher community adoption of Vue 3 may lead to better support, resources, and a larger talent pool of Vue 3 developers over time.

Conclusion

In conclusion, Vuex has long been a reliable state management solution for Vue.js applications, offering a centralized store, predictable state mutations, and seamless integration with Vue.js 2. However, with the introduction of Vue.js 3, Pinia emerges as a modern alternative to Vuex. Pinia provides similar features as Vuex but leverages Vue.js 3's Composition API for more intuitive state management.

Additionally, Pinia offers improved TypeScript support, better reactivity, and simplified syntax, making it an excellent choice for state management in Vue.js 3 applications. While Vuex remains a dependable option, Pinia's modern approach and flexibility position it as a compelling choice for state management in Vue.js 3 projects. Ultimately, the choice between Vuex and Pinia depends on project requirements, preferences, and compatibility with Vue.js versions.

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