download()
function of the
downloads
API downloads a file, given its URL and other optional preferences.
If the URL uses the HTTP or HTTPS protocol, the request includes all the relevant cookies, that is, those cookies set for the URL's hostname, secure flag, path, and so on. The default cookies, the cookies from the normal browsing session, are used unless:
incognito
option is used, then the private browsing cookies are used.
cookieStoreId
option is used, then the cookies from the specified store are used.
If both
filename
and
saveAs
are specified, the Save As dialog is displayed, populated with the
filename
.
This is an asynchronous function that returns a
Promise
.
var downloading = browser.downloads.download(
选项
// object
)
选项
An
对象
specifying what file you wish to download, and any other preferences you wish to set concerning the download. It can contain the following properties:
allowHttpErrors
可选
A
boolean
flag that enables downloads to continue even if they encounter HTTP errors. Using this flag, for example, enables the download of server error pages. Default value
false
. When set to:
false
, the download is canceled when it encounters an HTTP error.
true
, the download continues when an HTTP error is encountered and the HTTP server error is not reported. However, if the download fails due to file-related, network-related, user-related, or other error, that error is reported.
body
可选
A
string
representing the post body of the request.
conflictAction
可选
A string representing the action you want taken if there is a filename conflict, as defined in the
downloads.FilenameConflictAction
type (defaults to "uniquify" when it is not specified).
cookieStoreId
可选
The cookie store ID of the contextual identity the download is associated with. If omitted, the default cookie store is used. Use requires the "cookies" API permission .
filename
可选
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, path components that start and/or end with a dot (.), 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.
headers
可选
If the URL uses the HTTP or HTTPS protocols, an
array
of
对象
representing additional HTTP headers to send with the request. Each header is represented as a dictionary object containing the keys
名称
and either
value
or
binaryValue
. The headers that are forbidden by
XMLHttpRequest
and
fetch
cannot be specified, however, Firefox 70 and later enables the use of the
Referer
header. Attempting to use a forbidden header throws an error.
incognito
可选
A
boolean
: if present and set to true, then associate this download with a private browsing session. This means that it will only appear in the download manager for any private windows that are currently open.
方法
可选
A
string
representing the HTTP method to use if the
url
uses the HTTP[S] protocol. This may be either "GET" or "POST".
saveAs
可选
A
boolean
that specifies whether to provide a file chooser dialog to allow the user to select a filename (
true
), or not (
false
).
If this option is omitted, the browser will show the file chooser or not based on the general user preference for this behavior (in Firefox this preference is labeled "Always ask you where to save files" in about:preferences, or
browser.download.useDownloadDir
in about:config).
注意：
Firefox for Android raises an error if
saveAs
被设为
true
. The parameter is ignored when
saveAs
is
false
or not included.
url
A
string
representing the URL to download.
A
Promise
. If the download started successfully, the promise will be fulfilled with the
id
of the new
downloads.DownloadItem
. Otherwise, the promise will be rejected with an error message taken from
downloads.InterruptReason
.
若使用 URL.createObjectURL() to download data created in JavaScript and you want to revoke the object URL (with revokeObjectURL ) later (as it is strongly recommended), you need to do that after the download has been completed. To do so, listen to the downloads.onChanged 事件。
BCD tables only load in the browser
The following snippet attempts to download an example file, also specifying a filename and location to save it in, and the
uniquify
conflictAction
选项。
function onStartedDownload(id) {
console.log(`Started downloading: ${id}`);
}
function onFailed(error) {
console.log(`Download failed: ${error}`);
}
var downloadUrl = "https://example.org/image.png";
var downloading = browser.downloads.download({
url : downloadUrl,
filename : 'my-image-again.png',
conflictAction : 'uniquify'
});
downloading.then(onStartedDownload, onFailed);
注意：
This API is based on Chromium's
chrome.downloads
API。
最后修改： , 由 MDN 贡献者