react-beautiful-dnd/src/view/drag-handle/util/create-event-marshal.js

Beautiful, accessible drag and drop for lists with React.js

// @flow
import invariant from 'tiny-invariant';

export type EventMarshal = {|
  handle: () => void,
  isHandled: () => boolean,
  reset: () => void,
|};

export default (): EventMarshal => {
  let isMouseDownHandled: boolean = false;

  const handle = (): void => {
    invariant(
      !isMouseDownHandled,
      'Cannot handle mouse down as it is already handled',
    );
    isMouseDownHandled = true;
  };

  const isHandled = (): boolean => isMouseDownHandled;

  const reset = (): void => {
    isMouseDownHandled = false;
  };

  return {
    handle,
    isHandled,
    reset,
  };
};