React Gantt - XState Tutorial

This tutorial will guide you through creating a React TypeScript application with Vite, integrating DHTMLX React Gantt component, and managing state with XState.

Prerequisites

• Basic knowledge of React, TypeScript, Vite, and XState
• Recommended: read Basics to understand the data binding mode and the data.save callback this tutorial builds on.

Quick setup - create the project

Before you start, install Node.js.

Create a Vite React + TypeScript project:

npm create vite@latest react-gantt-xstate-demo -- --template react-ts  
cd react-gantt-xstate-demo  

Now let's install the required dependencies.

• For npm:

npm install xstate @xstate/react @mui/material @mui/icons-material @emotion/react @emotion/styled

• For yarn:

yarn add xstate @xstate/react @mui/material @mui/icons-material @emotion/react @emotion/styled

Then we need to install the React Gantt package.

Installing React Gantt

Install React Gantt as described in .

In this tutorial we use the evaluation package:

npm install @dhtmlx/trial-react-gantt

or

yarn add @dhtmlx/trial-react-gantt

If you already use the Professional package, replace @dhtmlx/trial-react-gantt with @dhx/react-gantt in the commands and imports.

Now you can start the dev server:

npm run dev 

You should now have your React project running on http://localhost:5173.

note

To make Gantt occupy the entire space of the body, you need to remove the default styles from the App.css file located in the src folder and add the following one:

#root { 
  margin: 0; 
  padding: 0; 
  height: 100%; 
  width: 100%; 
} 

Setting Up Sample Data and Configuration

Create sample data for our Gantt chart in src/seed/Seed.ts which will contain the initial data:

import type { SerializedTask, Link, GanttConfig } from '@dhtmlx/trial-react-gantt';

export type ZoomLevel = 'day' | 'month' | 'year';

export const defaultZoomLevels: NonNullable<GanttConfig['zoom']> = { 
  current: 'day', 
  levels: [ 
  { name: 'day', scale_height: 27, min_column_width: 80, scales: [{ unit: 'day', step: 1, format: '%d %M' }] }, 
  { name: 'month', scale_height: 50, min_column_width: 120, scales: [{ unit: 'month', format: '%F, %Y' }, { unit: 'week', format: 'Week #%W' }] }, 
  { name: 'year', scale_height: 50, min_column_width: 30, scales: [{ unit: 'year', step: 1, format: '%Y' }] }, 
  ], 
};

export const seedTasks: SerializedTask[] = [ 
  { id: 1, text: 'Office itinerancy', type: 'project', start_date: new Date(2025, 3, 2).toISOString(), duration: 17, progress: 0.4, parent: 0, open: true }, 
  { id: 2, text: 'Office facing', type: 'project', start_date: new Date(2025, 3, 2).toISOString(), duration: 8, progress: 0.6, parent: 1, open: true }, 
  { id: 3, text: 'Furniture installation', type: 'project', start_date: new Date(2025, 3, 11).toISOString(), duration: 8, progress: 0.6, parent: 1, open: true }, 
  { id: 4, text: 'The employee relocation', type: 'project', start_date: new Date(2025, 3, 13).toISOString(), duration: 5, progress: 0.5, parent: 1, priority: 3, open: true }, 
  { id: 5, text: 'Interior office', type: 'task', start_date: new Date(2025, 3, 3).toISOString(), duration: 7, progress: 0.6, parent: 2, priority: 1 }, 
  { id: 6, text: 'Air conditioners check', type: 'task', start_date: new Date(2025, 3, 3).toISOString(), duration: 7, progress: 0.6, parent: 2, priority: 2 }, 
  { id: 7, text: 'Workplaces preparation', type: 'task', start_date: new Date(2025, 3, 12).toISOString(), duration: 8, progress: 0.6, parent: 3 }, 
  { id: 8, text: 'Preparing workplaces', type: 'task', start_date: new Date(2025, 3, 14).toISOString(), duration: 5, progress: 0.5, parent: 4, priority: 1 }, 
  { id: 9, text: 'Workplaces importation', type: 'task', start_date: new Date(2025, 3, 21).toISOString(), duration: 4, progress: 0.5, parent: 4 }, 
  { id: 10, text: 'Workplaces exportation', type: 'task', start_date: new Date(2025, 3, 27).toISOString(), duration: 3, progress: 0.5, parent: 4, priority: 2 }
];

export const seedLinks: Link[] = [ 
  { id: 2, source: 2, target: 3, type: '0' },
  { id: 3, source: 3, target: 4, type: '0' },
  { id: 7, source: 8, target: 9, type: '0' }
]; 

Building the Control Toolbar Component

Now, let's add a Toolbar component in src/components/Toolbar.tsx.

This component gives users quick access to common Gantt controls, like zooming between day, month, and year views, and performing undo/redo actions.

import Divider from '@mui/material/Divider';  
import ButtonGroup from '@mui/material/ButtonGroup';  
import UndoIcon from '@mui/icons-material/Undo';  
import RedoIcon from '@mui/icons-material/Redo';  
import Button from '@mui/material/Button';  
import type { ZoomLevel } from '../seed/Seed';

export interface ToolbarProps {  
  onUndo?: () => void;  
  onRedo?: () => void;  
  onZoom?: (level: ZoomLevel) => void;  
  currentZoom?: ZoomLevel;  
}

export default function Toolbar({ onUndo, onRedo, onZoom, currentZoom = 'month' }: ToolbarProps) {  
  return (  
    <div style={{ display: 'flex', justifyContent: 'start', padding: '10px 10px 20px', gap: '10px' }}>  
      <ButtonGroup>  
        <Button onClick={() => onUndo?.()}>  
          <UndoIcon />  
        </Button>  
        <Button onClick={() => onRedo?.()}>  
          <RedoIcon />  
        </Button>  
      </ButtonGroup>  
      <Divider orientation="vertical"></Divider>  
      <ButtonGroup>  
        <Button onClick={() => onZoom?.('day')} variant={currentZoom === 'day' ? 'contained' : 'outlined'}>  
          Day  
        </Button>  
        <Button onClick={() => onZoom?.('month')} variant={currentZoom === 'month' ? 'contained' : 'outlined'}>  
          Month  
        </Button>  
        <Button onClick={() => onZoom?.('year')} variant={currentZoom === 'year' ? 'contained' : 'outlined'}>  
          Year  
        </Button>  
      </ButtonGroup>  
    </div>  
  );  
}

We use Material UI components (Button, ButtonGroup, Divider, and icons) to create a simple, clean toolbar layout that provides intuitive controls for the Gantt chart.

The toolbar accepts the following optional props that enable seamless integration with our XState machine:

• onUndo and onRedo - callback functions that dispatch undo/redo events to our state machine.
• onZoom - a callback that sends zoom update events to our machine when users click zoom buttons
• currentZoom - indicates which zoom level is currently active, allowing the toolbar to highlight the selected button

The buttons for "Day", "Month", and "Year" call onZoom('day'), onZoom('month'), or onZoom('year') respectively. The selected zoom level button uses variant="contained", while the others are outlined, providing a clear visual cue for the current state.

The toolbar connects directly to our XState machine through event dispatching:

• Zoom Controls: When a user clicks "Day", we send a SET_ZOOM event with the level to our state machine, which updates the Gantt chart's configuration through predefined actions
• The Undo button sends an UNDO event to the machine, triggering the undo action to revert to previous states, while the Redo button sends a REDO event to reapply changes
• All state changes (task edits, deletions, zoom adjustments, etc.) are handled as discrete events in our state machine and can be reversed or reapplied through the history system

Creating the Main Gantt Component

Let's start by building our main component that will host the Gantt chart. Create src/components/GanttComponent.tsx.

First, we import useEffect, useMemo, and useRef from React, the main ReactGantt component and types from the Gantt package, our custom Toolbar component, and the ganttMachine definition from the XState setup:

import { useCallback, useEffect, useMemo } from 'react';
import { useMachine } from '@xstate/react';
import ReactGantt, {
  type ReactGanttRef,
  type ReactGanttProps,
  type Link,
  type SerializedTask,
} from '@dhtmlx/trial-react-gantt';
import '@dhtmlx/trial-react-gantt/dist/react-gantt.css';

import Toolbar from './Toolbar';
import { ganttMachine } from '../machine';
import { type ZoomLevel } from '../seed/Seed';

Now, let's set up the component and connect it to our XState machine:

export default function DemoXState() {  
  const [state, send] = useMachine(ganttMachine);  
  const ganttRef = useRef<ReactGanttRef>(null);

  useEffect(() => {  
    document.title = 'DHTMLX React Gantt | XState';  
  }, []);
}

• We use the useMachine hook from @xstate/react to connect our component to the state machine
• The hook returns the current state and a send function for dispatching events to the machine
• ganttRef provides direct access to the Gantt instance for imperative operations
• useEffect sets the document title when the component mounts

Let's configure the Gantt chart's templates which define date formatting and parsing for consistent data handling and event handlers:

const templates: ReactGanttProps['templates'] = useMemo(  
  () => ({  
    format_date: (d) => d.toISOString(),  
    parse_date: (s) => new Date(s),  
  }),  
  []  
);

const handleUndo = useCallback(() => {  
  send({ type: 'UNDO' });  
}, [send]);

const handleRedo = useCallback(() => {  
  send({ type: 'REDO' });  
}, [send]);

const handleZoom = useCallback(  
  (level: ZoomLevel) => {  
    send({ type: 'SET_ZOOM', level });  
  },  
  [send]  
);

We use useCallback to memoize event handlers for undo, redo, and zoom operations, which prevents unnecessary re-renders of child components when the component updates. Each handler dispatches a specific event type to the state machine with the required payload.

The most critical part - connecting Gantt data changes to our XState machine:

const data: ReactGanttProps['data'] = useMemo(  
  () => ({  
    save: (entity, action, item, id) => {  
      if (entity === 'task') {  
        const task = item as SerializedTask;  
        if (action === 'create') {  
          send({ type: 'ADD_TASK', task });  
        } else if (action === 'update') {  
          send({ type: 'UPSERT_TASK', task });  
        } else if (action === 'delete') {  
          send({ type: 'DELETE_TASK', id });  
        }  
      } else if (entity === 'link') {  
        const link = item as Link;  
        if (action === 'create') {  
          send({ type: 'ADD_LINK', link });  
        } else if (action === 'update') {  
          send({ type: 'UPSERT_LINK', link });  
        } else if (action === 'delete') {  
          send({ type: 'DELETE_LINK', id });  
        }  
      }  
    },  
  }),  
  [send]  
);

• The data.save callback handles all data modifications from the Gantt chart
• It routes different operations (create, update, delete) to appropriate machine events using the send function
• Each user action in the Gantt chart becomes a discrete event sent to the state machine
• The dependency array ensures the callback updates when the send function changes

If you need a deeper explanation of this callback, see Handling changes with data.save in the Basics guide.

Finally, we render the complete component:

return (  
  <div style={{ height: '100%', display: 'flex', flexDirection: 'column' }}>  
    <Toolbar  
      onUndo={handleUndo}  
      onRedo={handleRedo}  
      currentZoom={state.context.config.zoom.current}  
      onZoom={handleZoom}  
    />  
    <ReactGantt  
      ref={ganttRef}  
      tasks={state.context.tasks}  
      links={state.context.links}  
      config={state.context.config}  
      templates={templates}  
      data={data}  
    />  
  </div>  
);  

• The Toolbar receives event handlers that dispatch UNDO, REDO, and SET_ZOOM events to the state machine
• The ReactGantt component receives all data (tasks, links, config) from the machine's context

And then update your src/App.tsx to use our Gantt component:

import './App.css';  
import GanttComponent from './components/GanttComponent';

function App() {  
  return (  
    <div style={{ width: '95vw', height: '100vh' }}>  
      <GanttComponent />  
    </div>  
  );  
}  
export default App;

Setting Up the XState Machine

Now let's create our state management solution using XState. Create src/machine.ts:

import { createMachine, assign } from 'xstate';  
import type { Link, GanttConfig, SerializedTask } from '@dhtmlx/trial-react-gantt';  
import { seedTasks, seedLinks, defaultZoomLevels, type ZoomLevel } from './seed/Seed';

export interface Snapshot {  
  tasks: SerializedTask[];  
  links: Link[];  
  config: GanttConfig;  
}

export interface ContextType {  
  tasks: SerializedTask[];  
  links: Link[];  
  config: GanttConfig;

  past: Snapshot[];  
  future: Snapshot[];  
  maxHistory: number;  
}

• We define TypeScript interfaces for the machine's context and snapshot structure
• ContextType defines all Gantt-related state including tasks, links, configuration, and history tracking
• Snapshot interface represents the state structure for undo/redo functionality

Now we define the event types that our machine will handle:

type SetZoomEvent = { type: 'SET_ZOOM'; level: ZoomLevel };  
type UndoEvent = { type: 'UNDO' };  
type RedoEvent = { type: 'REDO' };  
type AddTaskEvent = { type: 'ADD_TASK'; task: SerializedTask };  
type UpsertTaskEvent = { type: 'UPSERT_TASK'; task: SerializedTask };  
type DeleteTaskEvent = { type: 'DELETE_TASK'; id: string | number };  
type AddLinkEvent = { type: 'ADD_LINK'; link: Link };  
type UpsertLinkEvent = { type: 'UPSERT_LINK'; link: Link };  
type DeleteLinkEvent = { type: 'DELETE_LINK'; id: string | number };

type EventType =  
  | SetZoomEvent  
  | UndoEvent  
  | RedoEvent  
  | AddTaskEvent  
  | UpsertTaskEvent  
  | DeleteTaskEvent  
  | AddLinkEvent  
  | UpsertLinkEvent  
  | DeleteLinkEvent;

• Each user interaction is represented as a discrete event with a specific type and payload
• Events are strongly typed, ensuring type safety across the entire application

Let's create the state machine configuration:

const createSnapshot = (ctx: ContextType): Snapshot => ({  
  tasks: structuredClone(ctx.tasks),  
  links: structuredClone(ctx.links),  
  config: structuredClone(ctx.config),  
});

export const ganttMachine = createMachine(  
  {  
    id: 'gantt',  
    types: {  
      context: {} as ContextType,  
      events: {} as EventType,  
    },  
    context: {  
      tasks: seedTasks,  
      links: seedLinks,  
      config: { zoom: defaultZoomLevels },  
      past: [],  
      future: [],  
      maxHistory: 50,  
    },  
    initial: 'ready',  
    states: {  
      ready: {  
        on: {  
          SET_ZOOM: { actions: ['pushHistory', 'setZoom'] },  
          UNDO: { actions: 'undo' },  
          REDO: { actions: 'redo' },

          ADD_TASK: { actions: ['pushHistory', 'addTask'] },  
          UPSERT_TASK: { actions: ['pushHistory', 'upsertTask'] },  
          DELETE_TASK: { actions: ['pushHistory', 'deleteTask'] },

          ADD_LINK: { actions: ['pushHistory', 'addLink'] },  
          UPSERT_LINK: { actions: ['pushHistory', 'upsertLink'] },  
          DELETE_LINK: { actions: ['pushHistory', 'deleteLink'] },  
        },  
      },  
    },  
  },
)

Machine Configuration:

• The machine has a single ready state where all Gantt operations are available
• Each event triggers a sequence of actions that update the machine's context
• The context defines the initial state with sample data and empty history arrays
• Event handlers specify which actions to execute when events are received

Now we implement the actions that handle state updates:

{  
  actions: {  
    pushHistory: assign(({ context }) => {  
      const snap = createSnapshot(context);  
      const past = [...context.past, snap];  
      if (past.length > context.maxHistory) past.shift();

      return {  
        past,  
        future: [],  
      };  
    }),  
    setZoom: assign(({ context, event }) => ({  
      config: {  
        ...context.config,  
        zoom: { ...context.config.zoom, current: (event as SetZoomEvent).level },  
      },  
    })),

    undo: assign(({ context }) => {  
      if (context.past.length === 0) return {};

      const previous = context.past[context.past.length - 1];  
      const future = [createSnapshot(context), ...context.future];

      return {  
        ...previous,  
        past: context.past.slice(0, -1),  
        future,  
      };  
    }),

    redo: assign(({ context }) => {  
      if (context.future.length === 0) return {};

      const next = context.future[0];  
      const past = [...context.past, createSnapshot(context)];

      return {  
        ...next,  
        past,  
        future: context.future.slice(1),  
      };  
    }),
  }
}

History Management Actions:

• pushHistory creates a snapshot of the current state and adds it to the history stack
• undo restores the previous state from the past array and moves current state to future
• redo reapplies the next state from future and saves current state to past

And let's implement the Gantt-specific data operations:

addTask: assign(({ context: ctx, event }) => ({  
  tasks: [...ctx.tasks, { ...(event as AddTaskEvent).task, id: `DB_ID:${(event as AddTaskEvent).task.id}` }],  
})),

upsertTask: assign(({ context: ctx, event }) => ({  
  tasks: ctx.tasks.map((task) =>  
    String(task.id) === String((event as UpsertTaskEvent).task.id)  
      ? { ...task, ...(event as UpsertTaskEvent).task }  
      : task  
  ),  
})),

deleteTask: assign(({ context, event }) => ({  
  tasks: context.tasks.filter((t) => String(t.id) !== String((event as DeleteTaskEvent).id)),  
})),

addLink: assign(({ context, event }) => ({  
  links: [...context.links, { ...(event as AddLinkEvent).link, id: `DB_ID:${(event as AddLinkEvent).link.id}` }],  
})),

upsertLink: assign(({ context, event }) => ({  
  links: context.links.map((l) =>  
    String(l.id) === String((event as UpsertLinkEvent).link.id) ? { ...l, ...(event as UpsertLinkEvent).link } : l  
  ),  
})),

deleteLink: assign(({ context, event }) => ({  
  links: context.links.filter((l) => String(l.id) !== String((event as DeleteLinkEvent).id)),  
})),  

• addTask creates new tasks with simulated database IDs and adds them to the task list
• upsertTask updates existing tasks by ID
• deleteTask removes tasks by ID from the task list
• Similar patterns are used for link operations (addLink, upsertLink, deleteLink)
• Each data modification action is paired with pushHistory to ensure undo/redo capability
• The assign function from XState is used to immutably update the machine's context

Run the application

Finally, we can run the dev server and test our application:

npm run dev

or:

yarn dev 

Summary

In this tutorial you've:

• created a Vite + React project
• added React Gantt and connected it to an XState machine via useMachine
• modeled tasks, links, and zoom configuration in the machine context
• implemented snapshot-based undo/redo using past/future history arrays and a pushHistory action
• used the data.save callback so that every change in the Gantt chart becomes a strongly typed XState event.

This keeps the Gantt component fully declarative, while all mutation logic and history handling live inside the state machine.

GitHub demo repository

A complete working project that follows this tutorial is provided on GitHub.

What's next

To go further:

• Revisit the concepts behind this example in Basics
• Combine XState machine with advanced configuration and templating in
• Compare this XState-driven architecture with other state managers:
  • Using React Gantt with Redux Toolkit
  • Using React Gantt with MobX
  • Using React Gantt with Zustand
  • Using React Gantt with Jotai
  • Using React Gantt with Valtio