The difference between Vue3 and Vue2: richer life cycle hooks

The difference between Vue3 and Vue2: richer life cycle hooks

Vue is a popular JavaScript framework for building interactive web applications. Vue2 is the stable version of Vue.js, while Vue3 is the latest version of Vue.js. Vue3 brings many improvements, one of which is richer lifecycle hooks. This article will introduce the difference between Vue3 and Vue2 life cycle hooks and demonstrate them through code examples.

Vue2 life cycle hooks
In Vue2, we have eight life cycle hooks that can be used:

1. beforeCreate: Called before the instance is created.
2. created: Called after the instance is created, but before it is mounted.
3. beforeMount: Called before DOM is mounted.
4. mounted: Called after the DOM is mounted.
5. beforeUpdate: Called before the component is updated.
6. updated: Called after the component is updated.
7. beforeDestroy: Called before the instance is destroyed.
8. destroyed: Called after the instance is destroyed.

These hooks can help us perform corresponding operations at different stages, such as performing some initialization settings after the instance is created, or performing some cleaning operations after the DOM is mounted and before destruction.

Vue3 life cycle hooks
Vue3 introduces new life cycle hooks, a total of ten:

1. beforeCreate: Same as in Vue2, called before the instance is created .
2. created: Same as in Vue2, called after the instance is created, but before mounting.
3. beforeMount: Same as in Vue2, called before the DOM is mounted.
4. mounted: Same as in Vue2, called after the DOM is mounted.
5. beforeUpdate: Same as in Vue2, called before the component is updated.
6. updated: Same as in Vue2, called after the component is updated.
7. beforeUnmount: Called before the component is unmounted.
8. unmounted: Called after the component is unmounted.
9. beforeDeactivate: Called before the component switches away.
10. deactivated: Called after the component switches away.

New lifecycle hooks give us better control over the different stages of a component.

Code Example
Let us demonstrate the difference between the life cycle hooks of Vue3 and Vue2 through a simple code example:

Vue2 Example:

Vue.component('my-component', {
  beforeCreate: function () {
    console.log('beforeCreate hook in Vue2');
  },
  created: function () {
    console.log('created hook in Vue2');
  },
  beforeMount: function () {
    console.log('beforeMount hook in Vue2');
  },
  mounted: function () {
    console.log('mounted hook in Vue2');
  },
  beforeUpdate: function () {
    console.log('beforeUpdate hook in Vue2');
  },
  updated: function () {
    console.log('updated hook in Vue2');
  },
  beforeDestroy: function () {
    console.log('beforeDestroy hook in Vue2');
  },
  destroyed: function () {
    console.log('destroyed hook in Vue2');
  },
  template: '<div>My Component</div>'
});

new Vue({
  el: '#app'
});

Vue3 Example:

const app = Vue.createApp({
  beforeCreate() {
    console.log('beforeCreate hook in Vue3');
  },
  created() {
    console.log('created hook in Vue3');
  },
  beforeMount() {
    console.log('beforeMount hook in Vue3');
  },
  mounted() {
    console.log('mounted hook in Vue3');
  },
  beforeUpdate() {
    console.log('beforeUpdate hook in Vue3');
  },
  updated() {
    console.log('updated hook in Vue3');
  },
  beforeUnmount() {
    console.log('beforeUnmount hook in Vue3');
  },
  unmounted() {
    console.log('unmounted hook in Vue3');
  },
  beforeDeactivate() {
    console.log('beforeDeactivate hook in Vue3');
  },
  deactivated() {
    console.log('deactivated hook in Vue3');
  },
  template: '<div>My Component</div>'
});

app.mount('#app');

Please note that in Vue3, use the Vue.createApp() method to create an application instance, and use the app.mount() method to mount the application to on DOM elements.

By running the above code example, you will see the console prints out the logs of different lifecycle hooks to show the differences between Vue3 and Vue2 in terms of lifecycle hooks.

Conclusion
Vue3 introduces richer life cycle hooks compared to Vue2, allowing us to better control the behavior of components at different stages. These lifecycle hook improvements make developing and maintaining Vue applications more convenient and flexible. I hope the code examples and explanations in this article will help you understand the life cycle hooks of Vue3 and Vue2.

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