Applet event binding

1. What is an event

Events are the means of communication from the rendering layer to the logical layer . Through events, the user's behavior in the render layer can be , Feed back to the logic layer for business processing

 2. Applet common events

type	Binding method	Description of the incident
tap	bindtap  or  bind:tap	Leave as soon as you touch your fingers , Be similar to  HTML  Medium  click  event
input	bindinput  or  bind:input	The input event of the text box
change	bindchange  or  bind:change	Triggered when the state changes

3. Property list of the event object

When the event callback is triggered , Will receive an event object event, Its detailed properties are as follows

attribute	type	explain
type	String	Event type
timeStamp	Integer	The number of milliseconds it took for the page to open to trigger the event
target	Object	A collection of property values for the component that triggered the event
currentTarget	Object	Some property value collections of the current component
detail	Object	Additional information
touches	Array	Touch event , An array of touch point information currently on the screen
changedTouches	Array	Touch event , Array of currently changing touchpoint information

4.target and currentTarget The difference between

        target Is the source component that triggered the event , and currentTarget Is the component bound by the current event

5.bindtap Grammar format

adopt bindtap Bind for component tap Touch event

<button bindtap="btnGet"> launch get request </button>

On page .js Define the corresponding event handling function in the file , The time parameter passes through the formal parameter event（ Generally abbreviated as e） To accept ：

  btnGet() {
    wx.request({
      url: 'https://applet-base-api-t.itheima.net/api/get',
      method: 'GET',
      data: {
        name: 'xiaoming',
        age: 12
      },
      success: (res) => {
        console.log(res.data)
      }
    })
  },

6. In the event handler function is data Data assignment in

      this.setData({
        canIUseGetUserProfile: true
      })

7. Event biography

Provided by components data-* Custom attribute transfer parameter ,* Represents the name of the parameter