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5.3.9 • Public • Published

@blockly/workspace-backpack Built on Blockly

A Blockly plugin that adds a Backpack to the workspace.



yarn add @blockly/workspace-backpack


npm install @blockly/workspace-backpack --save


Context Menus

The following context menu options are available for the backpack:

  • "Copy all Blocks" to Backpack in main Workspace
  • "Paste all Blocks" from Backpack in main Workspace
  • "Remove from Backpack" on Block stack in Backpack Flyout
  • "Copy to Backpack" on a Block stack in main Workspace
  • "Empty" option when right clicking the Backpack that is disabled if the Backpack is empty

An animated picture of all the context menu options in use


import * as Blockly from 'blockly';
import {Backpack} from '@blockly/workspace-backpack';

// Inject Blockly.
const workspace = Blockly.inject('blocklyDiv', {
  toolbox: toolboxCategories,

// Initialize plugin.
const backpack = new Backpack(workspace);


This plugin takes an optional configuration object.

  allowEmptyBackpackOpen: (boolean|undefined),
  useFilledBackpackImage: (boolean|undefined),
  skipSerializerRegistration: (boolean|undefined),
  contextMenu: {
    emptyBackpack: (boolean|undefined),
    removeFromBackpack: (boolean|undefined),
    copyToBackpack: (boolean|undefined),
    copyAllToBackpack: (boolean|undefined),
    pasteAllToBackpack: (boolean|undefined),
    disablePreconditionChecks: (boolean|undefined),

The configuration options are passed in to the constructor. In this configuration object, you can currently configure which context menu options are registered at init.

const backpackOptions = {
  allowEmptyBackpackOpen: true,
  useFilledBackpackImage: true,
  contextMenu: {
    emptyBackpack: true,
    removeFromBackpack: true,
    copyToBackpack: false,
const backpack = new Backpack(workspace, backpackOptions);

The following options are the default values used for any property in the passed in options that is undefined:

const defaultOptions = {
  allowEmptyBackpackOpen: true,
  useFilledBackpackImage: false,
  skipSerializerRegistration: false,
  contextMenu: {
    emptyBackpack: true,
    removeFromBackpack: true,
    copyToBackpack: true,
    copyAllToBackpack: false,
    pasteAllToBackpack: false,
    disablePreconditionChecks: false,

The allowEmptyBackpackOpen property, if set to false, will prevent the backpack flyout from being opened if the backpack is empty.

The useFilledBackpackImage property, if set to true, will change the backpack image when the backpack has something in it.

The skipSerializerRegistration property, if set to true, will not register the backpack serializer with the workspace serializer. Set this to true if you don't want the backpack to be serialized alongside the workspace.

The disablePreconditionChecks property will prevent the "Copy to Backpack" context menu option from disabling the context menu option if the block is already in the Backpack. Setting this flag to true to disable the check can be beneficial for performance if you expect blocks stacks to be very large.

An animated picture of the "Copy to Backpack" context menu

Note: Currently the empty Backpack context menu is registered globally, while the others are registered per workspace.

Blockly Languages

We do not currently support translating the text in this plugin to different languages. However, if you would like to support multiple languages the messages can be translated by assigning the following properties of Blockly.Msg

  • EMPTY_BACKPACK (Default: "Empty") context menu - Empty the backpack.
  • REMOVE_FROM_BACKPACK (Default: "Remove from Backpack") context menu - Remove the selected Block from the backpack.
  • COPY_TO_BACKPACK (Default: "Copy to Backpack") context menu - Copy the selected Block to the backpack.
  • COPY_ALL_TO_BACKPACK (Default: "Copy All Blocks to Backpack") Context menu - copy all Blocks on the workspace to the backpack.
  • PASTE_ALL_FROM_BACKPACK (Default: "Paste All Blocks from Backpack") context menu - Paste all Blocks from the backpack to the workspace.
Blockly.Msg['EMPTY_BACKPACK'] = 'Opróżnij plecak'; // Polish
// Inject workspace, etc...


  • init: Initializes the backpack.

  • dispose: Disposes of backpack.

  • getCount: Returns the count of items in the backpack.

  • getContents Returns backpack contents.

  • empty: Empties the backpack's contents. If the contents-flyout is currently open it will be closed.

  • addBlock: Adds Block to backpack.

  • addBlocks: Adds Blocks to backpack.

  • removeBlock: Removes Block to backpack.

  • addItem: Adds item to backpack.

  • removeItem: Removes item from the backpack.

  • setContents: Sets backpack contents.

  • isOpen: Returns whether the backpack is open.

  • open: Opens the backpack flyout.

  • close: Closes the backpack flyout.

  • handleBlockDrop: Handles a block drop on this backpack.

  • onDragEnter: Handle mouse over.

  • onDragExit: Handle mouse exit.

  • getBoundingRectangle: Returns the bounding rectangle of the UI element in pixel units relative to the Blockly injection div.

  • position: Positions the backpack UI element.


Multiple Backpacks per Workspace

This plugin also currently only supports one Backpack per Workspace.


This plugin registers a custom context menu by overriding Blockly.configureContextMenu in init in order to support the context menu for emptying the Backpack. If you also override Blockly.configureContextMenu after initializing this plugin, you must also call the old Blockly.configureContextMenu function. Example:

const prevConfigureContextMenu = workspace.configureContextMenu;
workspace.configureContextMenu = (menuOptions, e) => {
  prevConfigureContextMenu &&
      prevConfigureContextMenu.call(null, menuOptions, e);

Backpack Flyout

The Backpack Flyout uses the registered Flyout for either Blockly.registry.Type.FLYOUTS_HORIZONTAL_TOOLBOX or Blockly.registry.Type.FLYOUTS_VERTICAL_TOOLBOX, similar to the implementation for Blockly.Trashcan. If a custom class is registered for either of these types, then the Backpack Flyout may need to be tested for compatibility.


Apache 2.0

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