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UploadTask interface

Represents the process of uploading an object. Allows you to monitor and manage the upload.

Signature:

typescript

export interface UploadTask

Properties

Property	Type	Description
snapshot	UploadTaskSnapshot	A snapshot of the current task state.

Methods

Method	Description
cancel()	Cancels a running task. Has no effect on a complete or failed task.
catch(onRejected)	Equivalent to calling <code>then(null, onRejected)</code>.
on(event, nextOrObserver, error, complete)	Listens for events on this task.<!-- -->Events have three callback functions (referred to as <code>next</code>, <code>error</code>, and <code>complete</code>).<!-- -->If only the event is passed, a function that can be used to register the callbacks is returned. Otherwise, the callbacks are passed after the event.<!-- -->Callbacks can be passed either as three separate arguments <em>or</em> as the <code>next</code>, <code>error</code>, and <code>complete</code> properties of an object. Any of the three callbacks is optional, as long as at least one is specified. In addition, when you add your callbacks, you get a function back. You can call this function to unregister the associated callbacks.
pause()	Pauses a currently running task. Has no effect on a paused or failed task.
resume()	Resumes a paused task. Has no effect on a currently running or failed task.
then(onFulfilled, onRejected)	This object behaves like a Promise, and resolves with its snapshot data when the upload completes.

UploadTask.snapshot

A snapshot of the current task state.

Signature:

typescript

snapshot: UploadTaskSnapshot;

UploadTask.cancel()

Cancels a running task. Has no effect on a complete or failed task.

Signature:

typescript

cancel(): boolean;

Returns:

boolean

True if the cancel had an effect.

UploadTask.catch()

Equivalent to calling then(null, onRejected).

Signature:

typescript

catch(onRejected: (error: StorageError) => unknown): Promise<unknown>;

Parameters

Parameter	Type	Description
onRejected	(error: StorageError<!-- -->) => unknown

Returns:

Promise<unknown>

UploadTask.on()

Listens for events on this task.

Events have three callback functions (referred to as next, error, and complete).

If only the event is passed, a function that can be used to register the callbacks is returned. Otherwise, the callbacks are passed after the event.

Callbacks can be passed either as three separate arguments or as the next, error, and complete properties of an object. Any of the three callbacks is optional, as long as at least one is specified. In addition, when you add your callbacks, you get a function back. You can call this function to unregister the associated callbacks.

Signature:

typescript

on(event: TaskEvent, nextOrObserver?: StorageObserver<UploadTaskSnapshot> | null | ((snapshot: UploadTaskSnapshot) => unknown), error?: ((a: StorageError) => unknown) | null, complete?: Unsubscribe | null): Unsubscribe | Subscribe<UploadTaskSnapshot>;

Parameters

Parameter	Type	Description
event	TaskEvent	The type of event to listen for.
nextOrObserver	StorageObserver<!-- --><UploadTaskSnapshot<!-- -->> \| null \| ((snapshot: UploadTaskSnapshot<!-- -->) => unknown)	The <code>next</code> function, which gets called for each item in the event stream, or an observer object with some or all of these three properties (<code>next</code>, <code>error</code>, <code>complete</code>).
error	((a: StorageError<!-- -->) => unknown) \| null	A function that gets called with a <code>StorageError</code> if the event stream ends due to an error.
complete	Unsubscribe \| null

Returns:

Unsubscribe | Subscribe<UploadTaskSnapshot>

If only the event argument is passed, returns a function you can use to add callbacks (see the examples above). If more than just the event argument is passed, returns a function you can call to unregister the callbacks.

Example 1

**Pass callbacks separately or in an object.**

javascript

var next = function(snapshot) {};
var error = function(error) {};
var complete = function() {};

// The first example.
uploadTask.on(
    firebase.storage.TaskEvent.STATE_CHANGED,
    next,
    error,
    complete);

// This is equivalent to the first example.
uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED, {
  'next': next,
  'error': error,
  'complete': complete
});

// This is equivalent to the first example.
var subscribe = uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED);
subscribe(next, error, complete);

// This is equivalent to the first example.
var subscribe = uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED);
subscribe({
  'next': next,
  'error': error,
  'complete': complete
});

Example 2

**Any callback is optional.**

javascript

// Just listening for completion, this is legal.
uploadTask.on(
    firebase.storage.TaskEvent.STATE_CHANGED,
    null,
    null,
    function() {
      console.log('upload complete!');
    });

// Just listening for progress/state changes, this is legal.
uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED, function(snapshot) {
  var percent = snapshot.bytesTransferred / snapshot.totalBytes * 100;
  console.log(percent + "% done");
});

// This is also legal.
uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED, {
  'complete': function() {
    console.log('upload complete!');
  }
});

Example 3

**Use the returned function to remove callbacks.**

javascript

var unsubscribe = uploadTask.on(
    firebase.storage.TaskEvent.STATE_CHANGED,
    function(snapshot) {
      var percent = snapshot.bytesTransferred / snapshot.totalBytes * 100;
      console.log(percent + "% done");
      // Stop after receiving one update.
      unsubscribe();
    });

// This code is equivalent to the above.
var handle = uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED);
unsubscribe = handle(function(snapshot) {
  var percent = snapshot.bytesTransferred / snapshot.totalBytes * 100;
  console.log(percent + "% done");
  // Stop after receiving one update.
  unsubscribe();
});

UploadTask.pause()

Pauses a currently running task. Has no effect on a paused or failed task.

Signature:

typescript

pause(): boolean;

Returns:

boolean

True if the operation took effect, false if ignored.

UploadTask.resume()

Resumes a paused task. Has no effect on a currently running or failed task.

Signature:

typescript

resume(): boolean;

Returns:

boolean

True if the operation took effect, false if ignored.

UploadTask.then()

This object behaves like a Promise, and resolves with its snapshot data when the upload completes.

Signature:

typescript

then(onFulfilled?: ((snapshot: UploadTaskSnapshot) => unknown) | null, onRejected?: ((error: StorageError) => unknown) | null): Promise<unknown>;

Parameters

Parameter	Type	Description
onFulfilled	((snapshot: UploadTaskSnapshot<!-- -->) => unknown) \| null	The fulfillment callback. Promise chaining works as normal.
onRejected	((error: StorageError<!-- -->) => unknown) \| null	The rejection callback.

Returns:

Promise<unknown>