Understanding Vue's setup app hooks

title: Understanding Vue's setup app hooks
date: 2024/9/30
updated: 2024/9/30
author: cmdragon

excerpt:
Abstract: This article describes in detail the application of the setup function in Vue 3, including its concepts, features, usage, and importance. setup function, as the core of the compositing API, is called before the component is instantiated, and is used to set up responsive state, compute attributes, methods, and lifecycle hooks, and is supported for use in SSRs and CSRs.

categories:

front-end development

tags:

Vue
setup
subassemblies
responsive
Calculating Properties
life cycle
methodologies

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In Vue 3, thesetup Functions are a core part of the Composition API, providing developers with a new way to organize and use the logic of components. In thesetup Inside the function, you can define the responsive state of the component, calculated properties, methods, and lifecycle hooks, etc.

catalogs

What is the setup function?
Features of the setup Function
How to use the setup function
- 1. Creating responsive state
- 2. Defining calculation properties
- 3. Defining the methodology
- 4. Use of life cycle hooks
summarize

What is the setup function?

setup is a special lifecycle function called before the component is instantiated to set the responsive state, calculated properties, methods, and other functionality of the component. When the component is created, Vue will first call thesetup function and uses the object it returns as a responsive property of the component.

scope of action

Server-side and client-side：setup Can be used in both server-side rendering (SSR) and client-side rendering (CSR).

Features of the setup Function

carry out ahead of time：setup Called before the component instance is created.
return value: An object can be returned, and the values will be available as properties and methods of the component that can be used in the template.
Access to props and context：setup The function takes two arguments:props cap (a poem)context(Containsattrs, slots, andemit）。
Responsive API support: You can use Vue's responsive APIs directly, such as theref cap (a poem)reactive。

How to use the setup function

1. Creating responsive state

utilizationref cap (a poem)reactive Perform status management:

<template>
  <div>
    <h1>{{ count }}</h1>
    <button @click="increment">Increment</button>
  </div>
</template>

<script setup>
import { ref } from 'vue';

const count = ref(0);

const increment = () => {
  ++;
};
</script>

2. Defining calculation properties

Calculating properties can be done with thecomputed to define:

<template>
  <div>
    <h1>{{ doubledCount }}</h1>
    <button @click="increment">Increment</button>
  </div>
</template>

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

const count = ref(0);

const increment = () => {
  ++;
};

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

3. Defining the methodology

This can be done in thesetup Define the method in and return it:

<template>
  <div>
    <h1>{{ message }}</h1>
    <button @click="changeMessage">Change Message</button>
  </div>
</template>

<script setup>
import { ref } from 'vue';

const message = ref('Hello, Vue 3!');

const changeMessage = () => {
   = 'Message Changed!';
};
</script>

4. Use of life cycle hooks

This can be done in thesetup Use lifecycle hooks such asonMounted cap (a poem)onUnmounted：

<template>
  <div>
    <h1>{{ count }}</h1>
    <button @click="increment">Increment</button>
  </div>
</template>

<script setup>
import { ref, onMounted, onUnmounted } from 'vue';

const count = ref(0);

const increment = () => {
  ++;
};

// utilization onMounted lifecycle hook
onMounted(() => {
  ('Component is mounted!');
});

// utilization onUnmounted lifecycle hook
onUnmounted(() => {
  ('Component is unmounted!');
});
</script>

summarize

setup Functions are a very powerful feature in Vue 3, allowing developers to organize component logic in a more flexible and modular way. This is accomplished through the judicious use of thesetup function and the API it provides, you can improve reusability and maintainability between components.

key point

Responsive state management: Useref cap (a poem)reactive Manage statuses with ease.
Calculation properties and methods: Bycomputed Define the calculation properties as well as the values in thesetup Define the method in the
lifecycle hook: can be found in thesetup Various lifecycle hooks are used to handle the lifecycle of components in the
optimize performance：setup The use of functions enables better organization of logic between components, improving performance and maintainability.

For the rest of the article, please click to jump to the personal blog page or scan the code to follow or WeChat search:Programming Intelligence Front-End to Full-Stack Communication and Growth, read the full article:Understanding Vue's setup app hooks | cmdragon's Blog

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