downloads.download()

The download() function of the downloads API downloads a file, given its URL and other optional preferences.

Other notes to bear in mind about download():

• If the specified url uses the HTTP or HTTPS protocol, then the request will include all cookies currently set for its hostname.
• If both filename and saveAs are specified, then the Save As dialog will be displayed, pre-populated with the specified filename.
• If the download started successfully and a callback was specified, it will be run with the new DownloadItem's id as a parameter.
• If there was an error starting the download and a callback was specified, it will be called with a downloadId parameter with a value of undefined.
• In any error case, runtime.lastError will contain a descriptive string. The error strings are not guaranteed to stay the same between releases.

Syntax

chrome.downloads.download(
  options,                   // object
  function(downloadId) {...} // optional function
)

This API is also available as browser.downloads.download() in a version that returns a promise.

Parameters

options

An object specifying what file you wish to download, and any other preferences you wish to set concerning the download. It can contain the following properties:

url

A string representing the URL to download.

filenameOptional

A string representing a file path relative to the default downloads directory — this provides the location where you want the file to be saved, and what filename you want to use. Absolute paths, empty paths, and paths containing back-references (../) will cause an error. If omitted, this value will default to the filename already given to the download file, and a location immediately inside the downloads directory.

conflictActionOptional

A string representing the action you want taken if there is a filename conflict, as defined in the downloads.FilenameConflictAction type.

saveAsOptional

A boolean that specifies whether to provide a file chooser dialog to allow the user to select a filename (true), or not (false).

methodOptional

A string representing the HTTP method to use if the url uses the HTTP[S] protocol.

headersOptional

An array of objects representing extra HTTP headers to send with the request if the URL uses the HTTP[s] protocol. Each header is represented as a dictionary object containing the keys name and either value or binaryValue, restricted to those allowed by XMLHttpRequest.

bodyOptional

A string representing the post body of the request.

function() {}Optional

An optional callback function, which, if included, is run when the download successfully starts. The function is passed the following arguments:

downloadId

An integer representing the id of the new downloads.DownloadItem.

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.

Compatibility notes

Firefox

• 'saveAs' is not supported.
• 'GET' is the only supported option for 'method'.

Examples

The following snippet attempts to download an example file, also specifying a filename and location to save it in, and the uniquify conflictAction option.

A callback function is defined to run when the download is started. Inside here we check whether runtime.lastError has been set, and log it to the console if is. If not, we log some information about the downloaded file to the console, after retrieving it by passing its id to downloads.search().

var btn = document.querySelector('button');

btn.onclick = function() {

  chrome.downloads.download({
      url : 'https://www.example.com/myImage.png',
      filename : 'images/myImage.png',
      conflictAction : 'uniquify' },
    callback);

  function callback(downloadId) {
    if(chrome.runtime.lastError) {
      console.log(chrome.runtime.lastError);
    } else {
      chrome.downloads.search({ id : downloadId }, function(results) {
        if(results[0].totalBytes === -1) {
          console.log('File downloading — ' +
                      'file size unknown; ' +
                      'the download was started at ' +
                      results[0].startTime + '.');
        } else {
          console.log('File downloading — ' +
                      'it is ' + results[0].totalBytes +
                      ' bytes in size, ' + 
                      ' and the download was started at ' +
                      results[0].startTime + '.');
        }
      });
    }
  }

}

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