downloads.onChanged

The onChanged() event of the downloads API is fired when any of a downloads.DownloadItem's properties changes (except for bytesReceived).

The listener is passed a downloadDelta as a parameter — an object containing the downloadId of the downloads.DownloadItem object in question, plus the status of all the properties that changed.

Syntax

chrome.downloads.onChanged.addListener(function(downloadDelta) {...})
chrome.downloads.onChanged.removeListener(listener)
chrome.downloads.onChanged.hasListener(listener)

This API is also available as browser.downloads.onChanged.*.

Events have three functions:

addListener(callback)

Adds a listener to this event.

removeListener(listener)

Stop listening to this event. The listener argument is the listener to remove.

hasListener(listener)

Check whether a given listener is registered for this event. Returns true if it is listening, false otherwise.

addListener syntax

Parameters

callback

A callback function that will be called when this event occurs. This function will be passed the following arguments:

downloadDelta

An object representing the downloads.DownloadItem object that changed, and the status of all the properties that changed in it.

Additional objects

downloadDelta

The downloadDelta object has the following properties available:

id

An integer representing the id of the downloads.DownloadItem that changed.

urlOptional

A downloads.StringDelta object describing a change in a downloads.DownloadItem's url.

filenameOptional

A downloads.StringDelta object describing a change in a downloads.DownloadItem's filename.

dangerOptional

A downloads.StringDelta object describing a change in a downloads.DownloadItem's danger.

mimeOptional

A downloads.StringDelta object describing a change in a downloads.DownloadItem's mime.

startTimeOptional

A downloads.StringDelta object describing a change in a downloads.DownloadItem's startTime.

endTimeOptional

A downloads.StringDelta object describing a change in a downloads.DownloadItem's endTime.

stateOptional

A downloads.StringDelta object describing a change in a downloads.DownloadItem's state.

canResumeOptional

A downloads.BooleanDelta object describing a change in a downloads.DownloadItem's canResume status.

pausedOptional

A downloads.BooleanDelta object describing a change in a downloads.DownloadItem's paused status.

errorOptional

A downloads.StringDelta object describing a change in a downloads.DownloadItem's error status.

totalBytesOptional

A downloads.DoubleDelta object describing a change in a downloads.DownloadItem's totalBytes.

fileSizeOptional

A downloads.DoubleDelta object describing a change in a downloads.DownloadItem's fileSize.

existsOptional

A downloads.BooleanDelta object describing a change in a downloads.DownloadItem's exists status.

Browser compatibility

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Examples

In this snippet we have a single button that when clicked, downloads a file via a call to downloads.download(). We also use the download.onChanged event and an associated handler to listen out for changes to the current downloads.DownloadItem's state property. When the downloads.DownloadItem's current state property is equal to complete (state below is a downloads.StringDelta, and we are checking it's current property), we log a message to the console to say that the download is complete.

var downloadBtn = document.querySelector('.download');

downloadBtn.onclick = function() {
  chrome.downloads.download({ url : 'https://www.example.com/myBigVideo.mp4'});
}

chrome.downloads.onChanged.addListener(function(downloadDelta) {
  if(downloadDelta.state.current === 'complete') {
    console.log('The download has completed.');
  }
});

// Copyright 2015 The Chromium Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//    * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//    * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//    * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.