# wx.miniapp.launchMiniProgram

App Pull up the WeChat Mini Program

# Precautions before Access

# parameter

alignmentWeChat opensdk Jump Mini ProgramParameters, easy to understand

attribute type Default value Required Introductions
userName string yes Mini Program original ID, such as gh_d43f693ca31f,[Click to see how to get it](https://dev.weixin.qq.com/docs/framework/faq/dev.html#_1, how to get the Mini Program original -id)
path string Default pull up Mini Program home page no Pull up the detachable path of the Mini Program page, such as: "?foo=bar"。
MiniprogramType number Default is the official version no Optional Open 0 - Official, 1 - Development, 2 - Experience
success function yes Successful callback after getting

# JSAPI Examples of code

// Login
 wx.miniapp.launchMiniProgram({
            userName: 'gh_d43f693ca31f',  //Mini Program Original ID
            path: 'originfiles/pages/miniapp/miniapp?action=login',
            MiniprogramType:  2, //0 Release ,1 test, 2 preview
            success: (res) => {
                wx.showModal({
                    content: res.data,
                })
                console.log('get wx phone number  success:', res)
            }
        })

# WeChat Mini Program Back to App

Developers can useButton Tags Jump back to App.

Note: in the case of Android, when SDK 1.2.17 In the case of the following version, the developer needs to carry the information of the app in the app-parameter to return the multi-terminal app normally, as follows. IOS doesn't need it.

When multi-terminal apps evoke WeChat mini-programs, they carry app-related information, which developers can get in the parameters of the onLoad function on the page.

The information obtained needs to be returned to the app in the app-parameter of the button tag. You can also bring information that the developer wishes to return.

Android App If you do not do the above, an error may occur:sendOpenReq failed:fail opensdk failed And did not return to the multi-terminal app through WeChat.


onLoad(res) {  
    // Page corresponds to the onLoad function to get information from the app
    transitiveData = res

    // The information brought by the app needs to use transitiveData as the key, and the developer's own data can be included in the data.
    const Data = {
        data: "MsgBackToApp" 
        transitiveData
    }

    // Set the required information into data, so that the button tag can get the
    this.setData({
        dataStr:  JSON.stringify(Data)
    })
}

<button open-type="launchApp" app-parameter="{{dataStr}}" bindtap="tap" >
Back to App
</button>