How to close the external component of vue

Vue.js is a progressive framework that allows you to easily build reusable components by combining various functions. Common Vue components are usually opened during some kind of interaction, but sometimes they also need to be closed under certain conditions. This article will introduce how to turn off event listening, timers, ajax requests and other resources outside components in Vue to avoid memory leaks and improve application performance.

1. Event listening

When a component is loaded, it often adds event listeners so that it can respond to various user operations during interaction. If these event listeners are not dismissed in time, memory leaks will occur, causing the application to slow down and eventually crash.

Solution: Before the component is destroyed, all event listeners of the component need to be removed. You can perform the following operations in the component's beforeDestroy hook function:

beforeDestroy() {
  window.removeEventListener('scroll', this.handleScroll);
  element.removeEventListener('click', this.handleClick);
}

The above code will remove the scroll event and click event listeners before the component is destroyed so that they no longer occupy memory.

2. Timer

Timer is another common problem that causes memory leaks. A common scenario is that a timer is created when a component is loaded, but if the component is unloaded before being destroyed, the timer will continue to run and occupy memory.

Solution: All timers need to be cleared before the component is destroyed. You can perform the following operations in the component's beforeDestroy hook function:

beforeDestroy() {
  clearInterval(this.timer);
}

The above code will clear all timers before the component is destroyed so that they no longer occupy memory.

3. Ajax request

Ajax request is a very common asynchronous operation. If a component creates an Ajax request and does not terminate it before the component is destroyed, the request will continue to occupy memory.

Solution: All outstanding Ajax requests need to be canceled before the component is destroyed. To achieve this, you can encapsulate all Ajax requests into Promise and cancel the request using the cancelToken function provided by axios. When the component is destroyed, cancel all outstanding requests under the component.

// 封装成Promise
const get = (url, data) => {
  return new Promise((resolve, reject) => {
    axios.get(url, {
      params: data,
      cancelToken: new axios.CancelToken(function(cancel) {
        // 将cancel存储在请求列表中
        requestList.push({ cancel });
      })
    })
    .then(res => {
      resolve(res.data);
    })
    .catch(err => {
      reject(err);
    });
  });
}

// 取消封装的请求
beforeDestroy() {
  // 取消所有未完成的请求
  requestList.forEach(item => item.cancel());
  // 清空取消列表
  requestList = [];
}

The above code encapsulates each request into a Promise and stores it in the request list so that it can be canceled. In the component destruction hook function, call the cancel function of each request to cancel all outstanding requests.

It is very important to release resources in Vue, not only to avoid memory leaks, but also to improve the performance of the application. If your component has added event listeners, timers, or Ajax requests, be sure to consider releasing these resources when closing the component.

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