chrome.fileSystemProvider

Description

Use the chrome.fileSystemProvider API to create file systems, that can be accessible from the file manager on Chrome OS.

Permissions

fileSystemProvider

Availability

ChromeOS only

Manifest

You must declare the "fileSystemProvider" permission and section in the extension manifest to use the File System Provider API. For example:

{
  "name": "My extension",
  ...
  "permissions": [
    "fileSystemProvider"
  ],
  ...
  "file_system_provider_capabilities": {
    "configurable": true,
    "watchable": false,
    "multiple_mounts": true,
    "source": "network"
  },
  ...
}

The file_system_provider section must be declared as follows:

configurable (boolean) - optional
Whether configuring via onConfigureRequested is supported. By default: false.
multiple_mounts (boolean) - optional
Whether multiple (more than one) mounted file systems are supported. By default: false.
watchable (boolean) - optional
Whether setting watchers and notifying about changes is supported. By default: false.
source (enum of "file", "device", or "network") - required
Source of data for mounted file systems.

Files app uses above information in order to render related UI elements appropriately. For example, if configurable is set to true, then a menu item for configuring volumes will be rendered. Similarly, if multiple_mounts is set to true, then Files app will allow to add more than one mount points from the UI. If watchable is false, then a refresh button will be rendered. Note, that if possible you should add support for watchers, so changes on the file system can be reflected immediately and automatically.

Overview

File System Provider API allows extensions to support virtual file systems, which are available in the file manager on ChromeOS. Use cases include decompressing archives and accessing files in a cloud service other than Drive.

Mounting file systems

Providing extensions can either provide file system contents from an external source (such as a remote server or a USB device), or using a local file (such as an archive) as its input.

In order to write file systems which are file handlers (source is "file") the provider must be a packaged app, as the onLaunched event is not available to extensions.

If the source is network or a device, then the file system should be mounted when onMountRequested event is called.

Source of the file system data Entry point
"file" Available to packaged apps only.
"device" or "network" onMountRequested

Configuring file systems

Provided file systems once mounted can be configured via the onConfigureRequested event. It's especially useful for file systems which provide contents via network in order to set proper credentials. Handling this event is optional.

Life cycle

Provided file systems once mounted are remembered by Chrome and remounted automatically after reboot or restart. Hence, once a file system is mounted by a providing extension, it will stay until either the extension is unloaded, or the extension calls the unmount method.

Types

AbortRequestedOptions

Properties

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • operationRequestId

    number

    An ID of the request to be aborted.

  • requestId

    number

    The unique identifier of this request.

Action

Chrome 45+

Properties

  • id

    string

    The identifier of the action. Any string or CommonActionId for common actions.

  • title

    string optional

    The title of the action. It may be ignored for common actions.

AddWatcherRequestedOptions

Properties

  • entryPath

    string

    The path of the entry to be observed.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • recursive

    boolean

    Whether observing should include all child entries recursively. It can be true for directories only.

  • requestId

    number

    The unique identifier of this request.

Change

Properties

  • changeType

    ChangeType

    The type of the change which happened to the entry.

  • cloudFileInfo

    CloudFileInfo optional

    Chrome 125+

    Information relating to the file if backed by a cloud file system.

  • entryPath

    string

    The path of the changed entry.

ChangeType

Type of a change detected on the observed directory.

Enum

"CHANGED"

"DELETED"

CloseFileRequestedOptions

Properties

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • openRequestId

    number

    A request ID used to open the file.

  • requestId

    number

    The unique identifier of this request.

CloudFileInfo

Chrome 125+

Properties

  • versionTag

    string optional

    A tag that represents the version of the file.

CloudIdentifier

Chrome 117+

Properties

  • id

    string

    The provider's identifier for the given file/directory.

  • providerName

    string

    Identifier for the cloud storage provider (e.g. 'drive.google.com').

CommonActionId

Chrome 45+

List of common actions. "SHARE" is for sharing files with others. "SAVE_FOR_OFFLINE" for pinning (saving for offline access). "OFFLINE_NOT_NECESSARY" for notifying that the file doesn't need to be stored for offline access anymore. Used by onGetActionsRequested and onExecuteActionRequested.

Enum

"SAVE_FOR_OFFLINE"

"OFFLINE_NOT_NECESSARY"

"SHARE"

ConfigureRequestedOptions

Chrome 44+

Properties

  • fileSystemId

    string

    The identifier of the file system to be configured.

  • requestId

    number

    The unique identifier of this request.

CopyEntryRequestedOptions

Properties

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • requestId

    number

    The unique identifier of this request.

  • sourcePath

    string

    The source path of the entry to be copied.

  • targetPath

    string

    The destination path for the copy operation.

CreateDirectoryRequestedOptions

Properties

  • directoryPath

    string

    The path of the directory to be created.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • recursive

    boolean

    Whether the operation is recursive (for directories only).

  • requestId

    number

    The unique identifier of this request.

CreateFileRequestedOptions

Properties

  • filePath

    string

    The path of the file to be created.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • requestId

    number

    The unique identifier of this request.

DeleteEntryRequestedOptions

Properties

  • entryPath

    string

    The path of the entry to be deleted.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • recursive

    boolean

    Whether the operation is recursive (for directories only).

  • requestId

    number

    The unique identifier of this request.

EntryMetadata

Properties

  • cloudFileInfo

    CloudFileInfo optional

    Chrome 125+

    Information that identifies a specific file in the underlying cloud file system. Must be provided if requested in options and the file is backed by cloud storage.

  • cloudIdentifier

    CloudIdentifier optional

    Chrome 117+

    Cloud storage representation of this entry. Must be provided if requested in options and the file is backed by cloud storage. For local files not backed by cloud storage, it should be undefined when requested.

  • isDirectory

    boolean optional

    True if it is a directory. Must be provided if requested in options.

  • mimeType

    string optional

    Mime type for the entry. Always optional, but should be provided if requested in options.

  • modificationTime

    Date optional

    The last modified time of this entry. Must be provided if requested in options.

  • name

    string optional

    Name of this entry (not full path name). Must not contain '/'. For root it must be empty. Must be provided if requested in options.

  • size

    number optional

    File size in bytes. Must be provided if requested in options.

  • thumbnail

    string optional

    Thumbnail image as a data URI in either PNG, JPEG or WEBP format, at most 32 KB in size. Optional, but can be provided only when explicitly requested by the onGetMetadataRequested event.

ExecuteActionRequestedOptions

Chrome 45+

Properties

  • actionId

    string

    The identifier of the action to be executed.

  • entryPaths

    string[]

    Chrome 47+

    The set of paths of the entries to be used for the action.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • requestId

    number

    The unique identifier of this request.

FileSystemInfo

Properties

  • displayName

    string

    A human-readable name for the file system.

  • fileSystemId

    string

    The identifier of the file system.

  • openedFiles

    OpenedFile[]

    List of currently opened files.

  • openedFilesLimit

    number

    The maximum number of files that can be opened at once. If 0, then not limited.

  • supportsNotifyTag

    boolean optional

    Chrome 45+

    Whether the file system supports the tag field for observing directories.

  • watchers

    Watcher[]

    Chrome 45+

    List of watchers.

  • writable

    boolean

    Whether the file system supports operations which may change contents of the file system (such as creating, deleting or writing to files).

GetActionsRequestedOptions

Chrome 45+

Properties

  • entryPaths

    string[]

    Chrome 47+

    List of paths of entries for the list of actions.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • requestId

    number

    The unique identifier of this request.

GetMetadataRequestedOptions

Properties

  • cloudFileInfo

    boolean

    Chrome 125+

    Set to true if cloudFileInfo value is requested.

  • cloudIdentifier

    boolean

    Chrome 117+

    Set to true if cloudIdentifier value is requested.

  • entryPath

    string

    The path of the entry to fetch metadata about.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • isDirectory

    boolean

    Chrome 49+

    Set to true if is_directory value is requested.

  • mimeType

    boolean

    Chrome 49+

    Set to true if mimeType value is requested.

  • modificationTime

    boolean

    Chrome 49+

    Set to true if modificationTime value is requested.

  • name

    boolean

    Chrome 49+

    Set to true if name value is requested.

  • requestId

    number

    The unique identifier of this request.

  • size

    boolean

    Chrome 49+

    Set to true if size value is requested.

  • thumbnail

    boolean

    Set to true if thumbnail value is requested.

MountOptions

Properties

  • displayName

    string

    A human-readable name for the file system.

  • fileSystemId

    string

    The string indentifier of the file system. Must be unique per each extension.

  • openedFilesLimit

    number optional

    The maximum number of files that can be opened at once. If not specified, or 0, then not limited.

  • persistent

    boolean optional

    Chrome 64+

    Whether the framework should resume the file system at the next sign-in session. True by default.

  • supportsNotifyTag

    boolean optional

    Chrome 45+

    Whether the file system supports the tag field for observed directories.

  • writable

    boolean optional

    Whether the file system supports operations which may change contents of the file system (such as creating, deleting or writing to files).

MoveEntryRequestedOptions

Properties

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • requestId

    number

    The unique identifier of this request.

  • sourcePath

    string

    The source path of the entry to be moved into a new place.

  • targetPath

    string

    The destination path for the copy operation.

NotifyOptions

Properties

  • changeType

    ChangeType

    The type of the change which happened to the observed entry. If it is DELETED, then the observed entry will be automatically removed from the list of observed entries.

  • changes

    Change[] optional

    List of changes to entries within the observed directory (including the entry itself)

  • fileSystemId

    string

    The identifier of the file system related to this change.

  • observedPath

    string

    The path of the observed entry.

  • recursive

    boolean

    Mode of the observed entry.

  • tag

    string optional

    Tag for the notification. Required if the file system was mounted with the supportsNotifyTag option. Note, that this flag is necessary to provide notifications about changes which changed even when the system was shutdown.

OpenedFile

Properties

  • filePath

    string

    The path of the opened file.

  • Whether the file was opened for reading or writing.

  • openRequestId

    number

    A request ID to be be used by consecutive read/write and close requests.

OpenFileMode

Mode of opening a file. Used by onOpenFileRequested.

Enum

"READ"

"WRITE"

OpenFileRequestedOptions

Properties

  • filePath

    string

    The path of the file to be opened.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • Whether the file will be used for reading or writing.

  • requestId

    number

    A request ID which will be used by consecutive read/write and close requests.

ProviderError

Error codes used by providing extensions in response to requests as well as in case of errors when calling methods of the API. For success, "OK" must be used.

Enum

"OK"

"FAILED"

"IN_USE"

"EXISTS"

"NOT_FOUND"

"ACCESS_DENIED"

"TOO_MANY_OPENED"

"NO_MEMORY"

"NO_SPACE"

"NOT_A_DIRECTORY"

"INVALID_OPERATION"

"SECURITY"

"ABORT"

"NOT_A_FILE"

"NOT_EMPTY"

"INVALID_URL"

"IO"

ReadDirectoryRequestedOptions

Properties

  • directoryPath

    string

    The path of the directory which contents are requested.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • isDirectory

    boolean

    Chrome 49+

    Set to true if is_directory value is requested.

  • mimeType

    boolean

    Chrome 49+

    Set to true if mimeType value is requested.

  • modificationTime

    boolean

    Chrome 49+

    Set to true if modificationTime value is requested.

  • name

    boolean

    Chrome 49+

    Set to true if name value is requested.

  • requestId

    number

    The unique identifier of this request.

  • size

    boolean

    Chrome 49+

    Set to true if size value is requested.

  • thumbnail

    boolean

    Chrome 49+

    Set to true if thumbnail value is requested.

ReadFileRequestedOptions

Properties

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • length

    number

    Number of bytes to be returned.

  • offset

    number

    Position in the file (in bytes) to start reading from.

  • openRequestId

    number

    A request ID used to open the file.

  • requestId

    number

    The unique identifier of this request.

RemoveWatcherRequestedOptions

Properties

  • entryPath

    string

    The path of the watched entry.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • recursive

    boolean

    Mode of the watcher.

  • requestId

    number

    The unique identifier of this request.

TruncateRequestedOptions

Properties

  • filePath

    string

    The path of the file to be truncated.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • length

    number

    Number of bytes to be retained after the operation completes.

  • requestId

    number

    The unique identifier of this request.

UnmountOptions

Properties

  • fileSystemId

    string

    The identifier of the file system to be unmounted.

UnmountRequestedOptions

Properties

  • fileSystemId

    string

    The identifier of the file system to be unmounted.

  • requestId

    number

    The unique identifier of this request.

Watcher

Properties

  • entryPath

    string

    The path of the entry being observed.

  • lastTag

    string optional

    Tag used by the last notification for the watcher.

  • recursive

    boolean

    Whether watching should include all child entries recursively. It can be true for directories only.

WriteFileRequestedOptions

Properties

  • data

    ArrayBuffer

    Buffer of bytes to be written to the file.

  • fileSystemId

    string

    The identifier of the file system related to this operation.

  • offset

    number

    Position in the file (in bytes) to start writing the bytes from.

  • openRequestId

    number

    A request ID used to open the file.

  • requestId

    number

    The unique identifier of this request.

Methods

get()

Promise 
chrome.fileSystemProvider.get(
  fileSystemId: string,
  callback?: function,
)

Returns information about a file system with the passed fileSystemId.

Parameters

  • fileSystemId

    string

  • callback

    function optional

    The callback parameter looks like: 

    (fileSystem: FileSystemInfo) => void

Returns

  • Promise<FileSystemInfo>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

getAll()

Promise 
chrome.fileSystemProvider.getAll(
  callback?: function,
)

Returns all file systems mounted by the extension.

Parameters

Returns

  • Promise<FileSystemInfo[]>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

mount()

Promise 
chrome.fileSystemProvider.mount(
  options: MountOptions,
  callback?: function,
)

Mounts a file system with the given fileSystemId and displayName. displayName will be shown in the left panel of the Files app. displayName can contain any characters including '/', but cannot be an empty string. displayName must be descriptive but doesn't have to be unique. The fileSystemId must not be an empty string.

Depending on the type of the file system being mounted, the source option must be set appropriately.

In case of an error, runtime.lastError will be set with a corresponding error code.

Parameters

  • options

    MountOptions

  • callback

    function optional

    The callback parameter looks like: 

    () => void

Returns

  • Promise<void>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

notify()

Promise Chrome 45+ 
chrome.fileSystemProvider.notify(
  options: NotifyOptions,
  callback?: function,
)

Notifies about changes in the watched directory at observedPath in recursive mode. If the file system is mounted with supportsNotifyTag, then tag must be provided, and all changes since the last notification always reported, even if the system was shutdown. The last tag can be obtained with getAll.

To use, the file_system_provider.notify manifest option must be set to true.

Value of tag can be any string which is unique per call, so it's possible to identify the last registered notification. Eg. if the providing extension starts after a reboot, and the last registered notification's tag is equal to "123", then it should call notify for all changes which happened since the change tagged as "123". It cannot be an empty string.

Not all providers are able to provide a tag, but if the file system has a changelog, then the tag can be eg. a change number, or a revision number.

Note that if a parent directory is removed, then all descendant entries are also removed, and if they are watched, then the API must be notified about the fact. Also, if a directory is renamed, then all descendant entries are in fact removed, as there is no entry under their original paths anymore.

In case of an error, runtime.lastError will be set will a corresponding error code.

Parameters

  • options

    NotifyOptions

  • callback

    function optional

    The callback parameter looks like: 

    () => void

Returns

  • Promise<void>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

unmount()

Promise 
chrome.fileSystemProvider.unmount(
  options: UnmountOptions,
  callback?: function,
)

Unmounts a file system with the given fileSystemId. It must be called after onUnmountRequested is invoked. Also, the providing extension can decide to perform unmounting if not requested (eg. in case of lost connection, or a file error).

In case of an error, runtime.lastError will be set with a corresponding error code.

Parameters

  • options

    UnmountOptions

  • callback

    function optional

    The callback parameter looks like: 

    () => void

Returns

  • Promise<void>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

Events

onAbortRequested

chrome.fileSystemProvider.onAbortRequested.addListener(
  callback: function,
)

Raised when aborting an operation with operationRequestId is requested. The operation executed with operationRequestId must be immediately stopped and successCallback of this abort request executed. If aborting fails, then errorCallback must be called. Note, that callbacks of the aborted operation must not be called, as they will be ignored. Despite calling errorCallback, the request may be forcibly aborted.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: AbortRequestedOptions, successCallback: function, errorCallback: function) => void

onAddWatcherRequested

Chrome 45+ 
chrome.fileSystemProvider.onAddWatcherRequested.addListener(
  callback: function,
)

Raised when setting a new directory watcher is requested. If an error occurs, then errorCallback must be called.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: AddWatcherRequestedOptions, successCallback: function, errorCallback: function) => void

onCloseFileRequested

chrome.fileSystemProvider.onCloseFileRequested.addListener(
  callback: function,
)

Raised when opening a file previously opened with openRequestId is requested to be closed.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: CloseFileRequestedOptions, successCallback: function, errorCallback: function) => void

onConfigureRequested

Chrome 44+ 
chrome.fileSystemProvider.onConfigureRequested.addListener(
  callback: function,
)

Raised when showing a configuration dialog for fileSystemId is requested. If it's handled, the file_system_provider.configurable manfiest option must be set to true.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: ConfigureRequestedOptions, successCallback: function, errorCallback: function) => void

onCopyEntryRequested

chrome.fileSystemProvider.onCopyEntryRequested.addListener(
  callback: function,
)

Raised when copying an entry (recursively if a directory) is requested. If an error occurs, then errorCallback must be called.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: CopyEntryRequestedOptions, successCallback: function, errorCallback: function) => void

onCreateDirectoryRequested

chrome.fileSystemProvider.onCreateDirectoryRequested.addListener(
  callback: function,
)

Raised when creating a directory is requested. The operation must fail with the EXISTS error if the target directory already exists. If recursive is true, then all of the missing directories on the directory path must be created.

Parameters

onCreateFileRequested

chrome.fileSystemProvider.onCreateFileRequested.addListener(
  callback: function,
)

Raised when creating a file is requested. If the file already exists, then errorCallback must be called with the "EXISTS" error code.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: CreateFileRequestedOptions, successCallback: function, errorCallback: function) => void

onDeleteEntryRequested

chrome.fileSystemProvider.onDeleteEntryRequested.addListener(
  callback: function,
)

Raised when deleting an entry is requested. If recursive is true, and the entry is a directory, then all of the entries inside must be recursively deleted as well.

Parameters

onExecuteActionRequested

Chrome 48+ 
chrome.fileSystemProvider.onExecuteActionRequested.addListener(
  callback: function,
)

Raised when executing an action for a set of files or directories is\ requested. After the action is completed, successCallback must be called. On error, errorCallback must be called.

Parameters

onGetActionsRequested

Chrome 48+ 
chrome.fileSystemProvider.onGetActionsRequested.addListener(
  callback: function,
)

Raised when a list of actions for a set of files or directories at entryPaths is requested. All of the returned actions must be applicable to each entry. If there are no such actions, an empty array should be returned. The actions must be returned with the successCallback call. In case of an error, errorCallback must be called.

Parameters

onGetMetadataRequested

chrome.fileSystemProvider.onGetMetadataRequested.addListener(
  callback: function,
)

Raised when metadata of a file or a directory at entryPath is requested. The metadata must be returned with the successCallback call. In case of an error, errorCallback must be called.

Parameters

onMountRequested

Chrome 44+ 
chrome.fileSystemProvider.onMountRequested.addListener(
  callback: function,
)

Raised when showing a dialog for mounting a new file system is requested. If the extension/app is a file handler, then this event shouldn't be handled. Instead app.runtime.onLaunched should be handled in order to mount new file systems when a file is opened. For multiple mounts, the file_system_provider.multiple_mounts manifest option must be set to true.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (successCallback: function, errorCallback: function) => void

    • successCallback

      function

      The successCallback parameter looks like: 

      () => void

    • errorCallback

      function

      The errorCallback parameter looks like: 

      (error: ProviderError) => void

onMoveEntryRequested

chrome.fileSystemProvider.onMoveEntryRequested.addListener(
  callback: function,
)

Raised when moving an entry (recursively if a directory) is requested. If an error occurs, then errorCallback must be called.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: MoveEntryRequestedOptions, successCallback: function, errorCallback: function) => void

onOpenFileRequested

chrome.fileSystemProvider.onOpenFileRequested.addListener(
  callback: function,
)

Raised when opening a file at filePath is requested. If the file does not exist, then the operation must fail. Maximum number of files opened at once can be specified with MountOptions.

Parameters

onReadDirectoryRequested

chrome.fileSystemProvider.onReadDirectoryRequested.addListener(
  callback: function,
)

Raised when contents of a directory at directoryPath are requested. The results must be returned in chunks by calling the successCallback several times. In case of an error, errorCallback must be called.

Parameters

onReadFileRequested

chrome.fileSystemProvider.onReadFileRequested.addListener(
  callback: function,
)

Raised when reading contents of a file opened previously with openRequestId is requested. The results must be returned in chunks by calling successCallback several times. In case of an error, errorCallback must be called.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: ReadFileRequestedOptions, successCallback: function, errorCallback: function) => void

    • successCallback

      function

      The successCallback parameter looks like: 

      (data: ArrayBuffer, hasMore: boolean) => void

      • data

        ArrayBuffer

      • hasMore

        boolean

    • errorCallback

      function

      The errorCallback parameter looks like: 

      (error: ProviderError) => void

onRemoveWatcherRequested

Chrome 45+ 
chrome.fileSystemProvider.onRemoveWatcherRequested.addListener(
  callback: function,
)

Raised when the watcher should be removed. If an error occurs, then errorCallback must be called.

Parameters

onTruncateRequested

chrome.fileSystemProvider.onTruncateRequested.addListener(
  callback: function,
)

Raised when truncating a file to a desired length is requested. If an error occurs, then errorCallback must be called.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: TruncateRequestedOptions, successCallback: function, errorCallback: function) => void

onUnmountRequested

chrome.fileSystemProvider.onUnmountRequested.addListener(
  callback: function,
)

Raised when unmounting for the file system with the fileSystemId identifier is requested. In the response, the unmount API method must be called together with successCallback. If unmounting is not possible (eg. due to a pending operation), then errorCallback must be called.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: UnmountRequestedOptions, successCallback: function, errorCallback: function) => void

onWriteFileRequested

chrome.fileSystemProvider.onWriteFileRequested.addListener(
  callback: function,
)

Raised when writing contents to a file opened previously with openRequestId is requested.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (options: WriteFileRequestedOptions, successCallback: function, errorCallback: function) => void