The role of created in vue

The created life cycle hook in Vue will be executed when the instance is created. Its functions include: 1. Data initialization, setting data before template rendering; 2. Initiating asynchronous operations to ensure completion before rendering; 3. Configuration Element, add event listener or style class before rendering; 4. Set watch listener to monitor data attribute changes.

The role of the created life cycle hook in Vue

The created life cycle hookwill be in Called when a Vue instance is created, it is executed between the data() and mounted() lifecycle hooks. Its function is as follows:

1. Perform data initialization

created life cycle hook is an ideal place to initialize data. It is called before the template is rendered, so any data set or updated in created will be available in the template. For example:

<code class="js">created() {
  this.message = 'Hello, Vue!';
}</code>

2. Initiate asynchronous operations

created Lifecycle hooks can also be used to initiate asynchronous operations, such as sending network requests or getting data from the backend. It ensures that these operations are completed before the template is rendered, thus avoiding loading delays. For example:

<code class="js">created() {
  axios.get('/api/data').then(response => {
    this.data = response.data;
  });
}</code>

3. Configuring elements

created Lifecycle hooks can also be used to configure DOM elements, such as setting up event listeners or adding style classes. This allows these configurations to be applied before the template is rendered, thus improving performance. For example:

<code class="js">created() {
  window.addEventListener('scroll', this.onScroll);
}

methods: {
  onScroll() {
    // 滚动处理逻辑
  }
}</code>

4. Set watch listener

created Life cycle hook can also be used to set watch listener, that is, to monitor changes in data attributes. This allows you to perform specific actions when data changes, such as validating or triggering other actions. For example:

<code class="js">created() {
  this.$watch('message', (newValue, oldValue) => {
    // 在 message 发生变化时执行特定操作
  });
}</code>

In short, the created life cycle hook is an important stage in the Vue instance creation process. It is used to initialize data, initiate asynchronous operations, configure elements and set watch listeners.

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