Modifiers let you dynamically modify the movement coordinates that are detected by sensors. They can be used for a wide range of use cases, for example:

• Restricting motion to a single axis
• Restricting motion to the draggable node container's bounding rectangle
• Restricting motion to the draggable node's scroll container bounding rectangle
• Applying resistance or clamping the motion

To start using modifiers, install the modifiers package via yarn or npm:

npm install @dnd-kit/modifiers

The modifiers repository contains a number of useful modifiers that can be applied on DndContext as well as DragOverlay.

import {DndContext, DragOverlay} from '@dnd-kit';
import {
  restrictToVerticalAxis,
  restrictToWindowEdges,
} from '@dnd-kit/modifiers';

function App() {
  return (
    <DndContext modifiers={[restrictToVerticalAxis]}>
      {/* ... */}
      <DragOverlay modifiers={[restrictToWindowEdges]}>
        {/* ... */}
      </DragOverlay>
    </DndContext>
  )
}

As you can see from the example above, DndContext and DragOverlay can both have different modifiers.

Restrict movement to only the horizontal axis.

Restrict movement to only the vertical axis.

Restrict movement to the edges of the window. This modifier can be useful to prevent the DragOverlay from being moved outside of the bounds of the window.

Restrict movement to the parent element of the draggable item that is picked up.

Restrict movement to the first scrollable ancestor of the draggable item that is picked up.

Function to create modifiers to snap to a given grid size.

import {createSnapModifier} from '@dnd-kit/modifiers';

const gridSize = 20; // pixels
const snapToGridModifier = createSnapModifier(gridSize);

To build your own custom modifiers, refer to the implementation of the built-in modifiers of @dnd-kit/modifiers: https://github.com/clauderic/dnd-kit/tree/master/packages/modifiers/src

For example, here is an implementation to create a modifier to snap to grid:

const gridSize = 20;

function snapToGrid(args) {
  const {transform} = args;
  
  return {
    ...transform,
    x: Math.ceil(transform.x / gridSize) * gridSize,
    y: Math.ceil(transform.y / gridSize) * gridSize,
  };
 }