Utilities

All of the utilities on this page are optional. You can also substitute them for your own similiar utilities if you want to.

draggables, drop targets and monitors return cleanup functions to remove their behaviour.

import {
  draggable,
  dropTargetForElements,
  monitorForElements,
} from '@atlaskit/pragmatic-drag-and-drop/element/adapter';

// You don't need to use this type explicitly, but including this import so you
// know where you can get the type if you want it.
import type { CleanupFn } from '@atlaskit/pragmatic-drag-and-drop/types';

const cleanupDraggable: CleanupFn = draggable({ element: myElement });
const cleanupDropTarget: CleanupFn = dropTargetForElements({
  element: myElement,
});
const cleanupMonitor: CleanupFn = monitorForElements({ element: myElement });

// unbind all functionality:
cleanupDraggable();
cleanupDropTarget();
cleanupMonitor();

combine is helpful to merge multiple cleanup functions into a single cleanup function.

const cleanup: CleanupFn = combine(
  draggable({ element: myElement }),
  dropTargetForElements({
    element: myElement,
  }),
  monitorForElements({ element: myElement }),
);

// unbind all functionality
cleanup();

Using combine() is helpful when working with react effects:

useEffect(() => {
  const cleanup = combine(
    draggable({ element: myElement }),
    dropTargetForElements({
      element: myElement,
    }),
    monitorForElements({ element: myElement }),
  );
  return cleanup;
}, []);

// or even simpler:
useEffect(() => {
  return combine(
    draggable({ element: myElement }),
    dropTargetForElements({
      element: myElement,
    }),
    monitorForElements({ element: myElement }),
  );
}, []);

A function that will only allow the provided function to be called once.

import { once } from '@atlaskit/pragmatic-drag-and-drop/once';

This is useful if your drop target getData() is expensive to calculate.

dropTargetForExternal({
  getData: once(getExpensiveData),
});

// calculate your data outside of get data
const data = getExpensiveData();
dropTargetForExternal({
  getData: () => data,
});

// have expensive data along with updated addons
const getDataOnce = once(getExpensiveData);
dropTargetForExternal({
  getData: ({ input, element }) => {
    const data = getDataOnce();
    return attachClosestEdge(data, { input, element, allowedEdges: ['top'] });
  },
});

A function to make common array reordering operations easier. It is helpful when reordering lists. reorder returns a new array and does not modify the provided list.

import { reorder } from '@atlaskit/pragmatic-drag-and-drop/reorder';

const reordered = reorder({
  list: [A, B, C],
  startIndex: 0,
  finishIndex: 1,
});

console.log(reordered); // [B, A, C]

In some situations, you want to explicitly allow "drop" operations to occur, even if no drop target accepts the drag. This is helpful for the following cases:

• Your are disabling a native drag preview and you want to prevent the default "cancel" animation on a cancelled drag
• You want to always prevent the default behaviour when dropping an external entity (eg prevent a file drop from opening a new page)

You can use preventUnhandled inside a monitor

import { monitorForExternal } from '@atlaskit/pragmatic-drag-and-drop/external/adapter';
import { preventUnhandled } from '@atlaskit/pragmatic-drag-and-drop/prevent-unhandled';
import { combine } from '@atlaskit/pragmatic-drag-and-drop/combine';

monitorForExternal({
  onDragStart: () => {
    // when any drag starts for files block unhandled drags
    preventUnhandled.start();
  },
});

preventUnhandled.start() only applies for the current drag operation. You need to call it again for each drag operation you want to use it for. You can use prevenUnhandled.stop() to stop blocking events during a drag operation if you like.

Pragmatic drag and drop has a specific entry point just for shared TypeScript types. You don't need to use these types explicitly as you can leverage inference, or use typeof to pull out the types you need (eg type CleanupFn = ReturnType<typeof draggable>).

In addition to these shared types, adapters also expose adapter specific types.

export type {
  // information about a drop target
  DropTargetRecord,

  // Used for coordinates
  // {x: number, y: number}
  Position,

  // What the current user input is
  Input,

  // Information about the current state of a drag.
  // Includes `Input` and `DropTargetRecord[]`
  DragLocation,

  // The `initial`, `current`, and `previous` `DragLocations`
  DragLocationHistory,

  // The type of our cleanup functions
  CleanupFn,

  // These types are not needed for consumers.
  // They are mostly helpful for other packages
  AllDragTypes,
  MonitorArgs,
  BaseEventPayload,
} from '@atlaskit/pragmatic-drag-and-drop/types';