scheduling | References | ArcGIS Maps SDK for JavaScript

import { schedule, addFrameTask } from "@arcgis/core/core/scheduling.js";

const { schedule, addFrameTask } = await $arcgis.import("@arcgis/core/core/scheduling.js");

Since: ArcGIS Maps SDK for JavaScript 4.7

Various utilities and convenience functions for executing code at various phases of browser frames. The scheduling module allows you to register tasks that are executed in every animation frame. This can be used to synchronize updates with ongoing animations of the view, or to animate the view manually by adjusting the extent or camera in every frame.

// Animate the scene view camera heading in every frame
let handle = scheduling.addFrameTask({
  update: function() {
    let camera = view.camera.clone();
    camera.heading += 0.2;
    view.camera = camera;
  }
});

// Remove frame task as soon as the user starts navigating in the view
reactiveUtils.whenOnce(() => view.navigating, () => handle.remove());

Type definitions

PhaseEvent

Type definition

An object with timing information.

time

Property

Type: number

The absolute time at the start of the current animation frame.

deltaTime

Property

Type: number

The elapsed time since the last animation frame.

elapsedFrameTime

Property

Type: number

The amount of time spent within the current animation frame. This can be used for budgeting (e.g. some tasks may already have run).

PhaseCallbacks

Type definition

A set of callbacks that will be called at specific phases of the animation frame.

prepare

Property

Type: PhaseCallback | undefined

A callback called before rendering.

render

Property

Type: PhaseCallback | undefined

A callback to execute rendering logic.

update

Property

Type: PhaseCallback | undefined

A callback to execute state update logic.

PhaseCallback

Type definition

A function called at a specific phase of the animation frame.

Parameters

Parameter	Type	Description	Required
event	PhaseEvent	An object with timing information.

Returns: void

FrameTaskHandle

Type definition

An object to remove or pause a frame task registered with addFrameTask().

remove

Method

Signature: remove (): void

Removes the frame task.

Returns: void

pause

Method

Signature: pause (): void

Pause the execution the frame task at every frame.

Returns: void

resume

Method

Signature: resume (): void

Resumes the execution the frame task.

Returns: void

Functions

schedule

Function

Schedules the execution of a callback function at the next web browser tick. Unlike addFrameTask(), a scheduled callback will only run once. Scheduling a task for the next execution tick can be useful when you want to throttle/accumulate functionality over a single javascript execution context.

Signature: schedule (callback: () => void): ResourceHandle

Parameters

Parameter	Type	Description	Required
callback	() => void	The function to call at the next tick.

Returns

ResourceHandle

Returns an scheduling handler with a remove() method that can be called to prevent the callback to be called at the next tick.

Property	Type	Description
remove	Function	When called, removes the callback from the callbacks queue.

Example

// Use scheduling.schedule to log an error message at most once per tick
let logErrorHandle;

function logError(error) {
  if (!logErrorHandle) {
    logErrorHandle = scheduling.schedule(function() {
      console.error(error);
      logErrorHandle = null;
    });
  }
});

addFrameTask

Function

Registers a frame task. An animation frame is composed of different phases to let various actors execute code before, after, or during the rendering of MapView or SceneView.

Signature: addFrameTask (phases: PhaseCallbacks): FrameTaskHandle

Parameters

Parameter	Type	Description	Required
phases	PhaseCallbacks	The callbacks for each phase of the frame.

Returns: FrameTaskHandle
A handle to remove, pause, or resume the frame task.

Example

// Animate the scene view camera heading in every frame
let handle = scheduling.addFrameTask({
  update: function() {
    let camera = view.camera.clone();
    camera.heading += 0.2;
    view.camera = camera;
  }
});

// Remove frame task as soon as the user starts navigating in the view
reactiveUtils.whenOnce(() => view.navigating, () => handle.remove());