# DownloadTask.onProgressUpdate(function callback)

Start from base library version 1.4.0. Please remaining backward compatible.

with Promise style call: Not supported

Mini Program plugin: Support

Listen for changes in download progress

# parameter

# function callback

Download callback functions for progress change events

# parameter

# Object res
attribute type Introductions
progress number Download progress percentage
totalBytesWritten number Length of data downloaded in units Bytes
totalBytesExpectedToWrite number Total length of data expected to be downloaded, in units Bytes