# API

The Weixin Mini Program development framework provides a rich WeChat native API that can easily activate the capabilities offered by WeChat, such as access to user information, local storage, payment functions, and so on.Please refer to the API documentation for details.

In general, the Weixin Mini Program API has the following types:

# Event Listening API

We agree that APIs starting withonare used to listen for an event to trigger, such as: wx.onSocketOpen , wx.onCompassChange et al.

This type of API accepts a callback function as a parameter, which is called when an event is triggered, and the relevant data is passed in as a parameter.

Code examples

wx.onCompassChange(function (res) {
  console.log(res.direction)
})

# Synchronization API

We agree that all APIs ending withSyncare synchronization APIs, such as wx.setStorageSync , wx.getSystemInfoSync etc.In addition, there are some other synchronization APIs, such as wx.createWorker , wx.getBackgroundAudioManager Etc. See instructions in the API documentation for details.

The result of the execution of the synchronization API can be obtained directly from the function return value, throwing an exception if the execution goes wrong.

Code examples

try {
  wx.setStorageSync('key', 'value')
} catch (e) {
  console.error(e)
}

# Asynchronous API

Most APIs are asynchronous APIs, such as wx.request , wx.login , etc.This type of API interface typically accepts aObjectparameter that supports specifying the following fields as needed to receive the result of the interface call:

Object parameter explaination

Parameters for callback functions

success，fail，completeThe function call passes a Object] type argument with the following fields:

The execution result of the asynchronous API needs to be obtained through the corresponding callback function passed in the parameter of typeObject.Some asynchronous APIs also have fallback values, which can be used to implement richer functionality, such as wx.request , wx.connectSocket etc.

Code examples

wx.login({
  success(res) {
    console.log(res.code)
  }
})

# Asynchronous API returns Promise

Since version {% version (2.10.2)%} of the base library, the asynchronous API supports callback and promise calls.When the interface parameter Object does not contain success / fail / complete, it will return a promise by default, otherwise it will still be executed by callback, no return value.

# Note

1. Some interfaces such asdownloadFile,request,uploadFile,connectSocket,createCamera（ MiniGame ）They have their own return values, and their promisify needs to be encapsulated by the developer.
2. When there is no callback parameter, the asynchronous interface returns a promise.If the function call fails to enter the fail logic, an error will occur Uncaught (in promise), developers can catch by catching.
3. Wx.onUnhandledRejection can listen for unhandled Promise rejection events.

Code examples

// Callback form call
wx.chooseImage({
  success(res) {
    console.log('res:', res)
  }
})

// Promise-Form Call
wx.chooseImage().then(res => console.log('res: ', res))

# Cloud Development API

When you open and use WeChat cloud development , you can use the cloud development API to directly call the cloud function on the Weixin Mini Program end.

Code examples

wx.cloud.callFunction({
  // 云函数名称
  name: 'cloudFunc',
  // 传给云函数的参数
  data: {
    a: 1,
    b: 2,
  },
  success: function(res) {
    console.log(res.result) // 示例
  },
  fail: console.error
})

// In addition, cloud functions also support promise form calls