Vue.js 3.0 Tutorial

Vue.js 3.0 Component Advanced

Vue.js 3.0 Transitions & Animations

Vue.js 3.0 Reusable & Combinable

Vue.js 3.0 Advanced

Vue.js 3.0 Tools

Vue.js 3.0 Scale

Vue.js 3.0 Accessibility

Vue.js 3.0 Migrating from Vue2

Vue.js 3.0 Contribute Documentation

Vue.js 3.0 API References

Vue.js 3.0 Style Guide

Vue 3.0 Style Guide

Vue 3.0 rendering mechanism and optimization

In Vue 3, the virtual DOM (vDOM) has been completely rewritten to enhance performance. Vue's new vDOM diffing algorithm is called 'Diffing with a Key-based Algorithm' and it has optimizations in both compilation and runtime.

Let's look at some of the improvements in Vue 3's rendering mechanism and how it optimizes the performance:

1. Static Tree Hoisting: Vue 3 is able to identify parts of the template that are static (i.e., they do not change between re-renders). These parts are hoisted outside the render function. This means they are only created once and then reused on subsequent renders, reducing the rendering time.

2. Patch Flagging: In Vue 2, when a component's state changed, the template would re-render and the diffing algorithm would be applied to the entire template. In Vue 3, a system of patch flags has been introduced. When a value within a template changes, Vue 3 flags the type of change that has occurred and only diffs that specific type of change. This reduces the amount of work Vue needs to do to update the DOM.

3. Fragment, Portal, Suspense: Vue 3 has introduced Fragments, Portals, and Suspense, which give developers more control over the rendering process. Fragments allow a component to have multiple root nodes. Portals allow for rendering a part of a template outside of Vue's root DOM node. Suspense is a special component that renders fallback content until a condition is met, it can be used to handle async dependencies in a component.

4. Compile-time Optimizations: Many of the optimizations Vue 3 performs happen at compile time when your application is being built, not at runtime when your application is being executed in the browser. This means that the user doesn't pay the performance cost of these optimizations. Some of these include - creating static nodes, creating static props, detecting on-click handlers that call only event.preventDefault(), etc.

Here's a simple example showing a performance improvement:

In Vue 2, for a component like this:

<template>
  <div>
    <p>{{ text }}</p>
    <button @click="count++">You clicked me {{ count }} times.</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      count: 0,
      text: 'Hello, Vue!'
    }
  }
}
</script>

The entire template re-renders when count changes. But in Vue 3, thanks to patch flagging, only the text content of the button element re-renders when count changes.

All these improvements and optimizations mean that Vue 3 is more efficient and performs better, especially in large applications with complex interfaces.

Vue 3.0 Reactivity System:

Description: Vue 3.0 introduces a reactivity system that efficiently tracks changes in data and automatically updates the DOM.

Code Example:

<script>
import { reactive } from 'vue';

const state = reactive({
  message: 'Hello Vue 3.0!',
});

// Changes to `state.message` trigger automatic updates in the DOM
</script>

Vue 3.0 Reactive Data and Computed Properties:

Code Example:

<script>
import { reactive, computed } from 'vue';

const state = reactive({
  count: 0,
});

const doubledCount = computed(() => state.count * 2);
</script>

Vue 3.0 Watch and Computed Properties Optimization:

Code Example:

<script>
import { ref, watchEffect } from 'vue';

const count = ref(0);

watchEffect(() => {
  console.log(count.value);
});
</script>

Vue 3.0 Render Functions and JSX:
- Description: Vue 3.0 allows using render functions and JSX for more fine-grained control over the DOM.
- Code Example:
```
<script>
export default {
  render() {
    return <div>Hello Vue 3.0 JSX!</div>;
  },
};
</script>
```

Memoization in Vue 3.0 for Rendering Optimization:

Code Example:

<script>
import { ref, computed } from 'vue';

const expensiveOperation = () => {
  // ... expensive operation
};

const result = ref(expensiveOperation());

// Use memoization to avoid recalculating unless dependencies change
const memoizedResult = computed(() => result.value);
</script>

Vue 3.0 Async Component Loading and Rendering:

Code Example:

<script>
const AsyncComponent = () => import('./AsyncComponent.vue');
</script>

Vue 3.0 Lazy Loading and Code Splitting for Optimization:

Code Example:

<script>
const LazyComponent = () => import('./LazyComponent.vue');
</script>