vue wait loop request

Vue is a popular JavaScript framework for building interactive web user interfaces. When using Vue, you often need to perform asynchronous operations, such as sending HTTP requests to obtain data or performing time-consuming tasks. In the case where these asynchronous operations require waiting for cyclic requests, Vue provides a variety of methods to effectively manage these requests.

1. What is a waiting loop request?

Waiting for loop request refers to the situation where when performing loop operation, it is necessary to wait for data to be returned before proceeding with the next loop. This situation is very common in web applications. For example, when you need to obtain data in batches or perform batch processing operations, you may need to wait for cyclic requests.

2. Why do we need to wait for circular requests?

In web applications, data processing and display are often asynchronous. If a set of data needs to be processed or displayed in the same way, looping is a very common method. However, if the amount of this set of data is very large, or the operation of processing or displaying the data is very time-consuming, then it may be necessary to wait for cyclic requests.

3. How to make a waiting loop request?

Vue provides a variety of methods to effectively manage wait loop requests, which are described in detail below.

1. Promise.all

The Promise.all method receives an array of Promise objects as parameters and returns a new Promise object. Only when all Promise objects are completed or one of them fails, the corresponding result can be obtained in the then or catch method. In the waiting loop request, we can wrap the operations that need to be looped with Promise, and then use the Promise.all method to wait for the execution results of all Promise objects.

The following is a simple example:

let promises = []
for (let i = 0; i < 5; i++) {
  promises.push(
    Axios.get('http://httpbin.org/get', {
      params: {
        id: i
      }
    })
  )
}

Promise.all(promises)
  .then(result => {
    console.log('请求完成', result)
  })
  .catch(error => {
    console.log('请求出错', error)
  })

In the above example, we sent five HTTP GET requests, using the Promise.all method to wait for all requests to complete. When all requests are completed, we will get all the request results in the then callback function and print them out.

2. async / await

async / await is an asynchronous programming solution introduced in ES7 to simplify the use of Promises. Using async / await can make asynchronous code look like synchronous code, increasing the readability and maintainability of the code. In the wait loop request, we can write the loop operation as an async function and use the await keyword to wait for the result of each loop.

The following is a simple example:

async function getRequests () {
  for (let i = 0; i < 5; i++) {
    let response = await Axios.get('http://httpbin.org/get', {
      params: {
        id: i
      }
    })
    console.log('请求完成', response.data)
  }
}

getRequests()

In the above example, we use the async function to encapsulate five HTTP GET requests, and use the await keyword to wait for the result of each request. When each request is completed, we will process the corresponding logic in the code, such as printing the request results.

3. Generator function

The Generator function is a new type of function introduced in ES6, which can be used to control the execution order of functions. In the wait loop request, we can write the loop operation as a Generator function and use the yield keyword to wait for the result of each loop.

The following is a simple example:

function *getRequests () {
  for (let i = 0; i < 5; i++) {
    let response = yield Axios.get('http://httpbin.org/get', {
      params: {
        id: i
      }
    })
    console.log('请求完成', response.data)
  }
}

let iterator = getRequests()
let result = iterator.next()

while (!result.done) {
  result.value.then(response => {
    result = iterator.next(response)
  })
}

In the above example, we use the Generator function to encapsulate five HTTP GET requests, and use the yield keyword to wait for the result of each request. When each request is completed, we will process the corresponding logic in the code, such as printing the request results.

4. Summary

Waiting loop requests are very common in web applications, and handling waiting loop requests in Vue is also very simple. By using various methods such as Promise.all method, async/await, Generator function, etc., we can effectively manage wait loop requests and optimize the readability and maintainability of the code. Of course, in practice, we need to choose the most appropriate method based on specific needs and scenarios.

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