uniapp network request asynchronous synchronization

In mobile application development, network requests are a common requirement. As a cross-platform development framework, uniapp provides a network request API, allowing developers to easily complete network request operations. In network requests, asynchronous and synchronous are two different methods. The following will introduce the asynchronous and synchronous methods of uniapp network requests.

1. uniapp asynchronous network request

Asynchronous network request means that after the request is issued, the main thread will not be blocked, but the request will be processed in the background thread. In uniapp, the asynchronous method of network requests is mainly completed through an API, namely uni.request. The API is called as follows:

uni.request({
  url: '',
  data: {},
  header: {},
  method: '',
  success: res => {},
  fail: () => {},
  complete: () => {}
})

The API receives an object as a parameter. The properties of the object are:

• url: Requested URL
• data: The requested data can be in JSON/XML and other formats
• header: Requested header information, such as Content-Type, etc.
• method: Requested method, such as GET/POST, etc.
• success: The callback function after the request is successful, the parameter is the data returned by the server
• fail: The callback function after the request fails
• complete: The callback function after the request is completed, whether successful or failed All callbacks

It should be noted that since asynchronous requests do not block the main thread, the request results cannot be returned directly. The request result needs to be passed to the callback function and processed in the callback function.

2. Uniapp Synchronous Network Request

Synchronous network request means that after the request is issued, the main thread will be blocked waiting for the request result to be returned. In uniapp, the API for synchronous requests is different from asynchronous requests, that is, uni.requestSync is used to send requests. The calling method of this API is as follows:

try {
  const [err, res] = uni.requestSync({
    url: '',
    data: {},
    header: {},
    method: ''
  })
  if (err) {
    console.error('请求失败')
  } else {
    console.log(res.data)
  }
} catch (e) {
  console.error('请求出错')
}

The parameters of this API also receive an object, but the difference is that its return value is an array, the first element is the error message, and the second element is the server The data returned. Since synchronous requests will block the main thread, use try-catch statements to catch exceptions.

3. The difference between asynchronous and synchronous

1. Blocking the main thread

Synchronous requests will block the main thread, causing the application to become unresponsive and the user experience will be poor. Difference. Asynchronous requests will not block the main thread, which can improve the response speed of the application and provide a better user experience.

2. Different processing methods

Since the synchronous request blocks the main thread, its return value can be used directly. Since asynchronous requests are processed in the background, the request results cannot be used directly and need to be processed through callback functions.

3. Different application scenarios

Synchronous requests are suitable for scenarios where data needs to be obtained before proceeding to the next step. For example, login requests require obtaining a token before continuing to access other pages. . Asynchronous requests are suitable for scenarios that need to be processed in the background, such as sending verification codes, uploading files, and other operations.

4. Summary

Whether it is an asynchronous request or a synchronous request, there are corresponding APIs in uniapp, which can be selected and used according to specific application scenarios. In actual development, it is necessary to choose which request method to use based on different business needs, so that the application can respond to user requests faster and more stably.

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