# wx.onBackgroundFetchData(function callback)
Start from base library version 2.8.0. Please remaining backward compatible.
with Promise style call: Not supported
Mini Program plugin: Not supported
Monitor received. backgroundFetch Callback at data time
# parameter
# function callback
Callback function
# parameter
# Object res
| attribute | type | Introductions |
|---|---|---|
| fetchType | string | Cache data category, with a value of periodic or pre |
| fetchedData | string | Cache data |
| timeStamp | number | The client gets the timestamp of the cached data |