Angular Data Grid Flatpickr

Angular Data GridFlatpickr Cell Type - Step-by-Step Guide

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Overview

This guide shows how to create a custom date picker cell using Flatpickr (opens new window), a powerful and flexible date picker library. This is more advanced than using native HTML5 date inputs, offering better cross-browser consistency and extensive customization options.

Difficulty: Intermediate Time: ~20 minutes Libraries: flatpickr, date-fns

What You'll Build

A cell that:

  • Displays formatted dates (e.g., "12/31/2024" or "31/12/2024")
  • Opens a beautiful calendar picker when edited
  • Supports per-column configuration (EU vs US date formats)
  • Handles locale-specific settings (first day of week)
  • Auto-closes and saves when a date is selected
  • Supports dark theme with dynamic stylesheet loading

Prerequisites

npm install flatpickr date-fns

Complete Example

Step 1: Import Dependencies

import Handsontable from 'handsontable/base';
import { registerAllModules } from 'handsontable/registry';
import { format, isDate } from 'date-fns';
import flatpickr from 'flatpickr';
import 'flatpickr/dist/flatpickr.css';
import { editorFactory } from 'handsontable/editors';
import { rendererFactory } from 'handsontable/renderers';

registerAllModules();

Why date-fns?

  • Lightweight, modular date formatting
  • Better than native toLocaleDateString() for consistency
  • Can be replaced with other libraries (moment, dayjs, etc.)
  • We import isDate for validation

Why editorFactory and rendererFactory?

  • editorFactory creates a custom editor with lifecycle hooks (init, beforeOpen, afterOpen, afterClose, getValue, setValue, etc.)
  • rendererFactory creates a custom renderer with access to cell properties
  • Both are Handsontable helpers that handle boilerplate like container creation, positioning, and lifecycle management

Step 2: Define Date Formats

const DATE_FORMAT_US = 'MM/dd/yyyy';
const DATE_FORMAT_EU = 'dd/MM/yyyy';

Why constants?

  • Reusability across renderer and column configuration
  • Single source of truth
  • Easy to add more formats (ISO, custom, etc.)

Step 3: Create the Renderer

The renderer displays the date in a human-readable format.

renderer: rendererFactory(({ td, value, cellProperties }) => {
  td.innerText = value ? format(new Date(value), cellProperties.renderFormat) : '';
})

What's happening:

  • value is the raw date value (e.g., ISO string "2025-03-15")
  • Empty or invalid values are shown as an empty string
  • cellProperties.renderFormat is a custom property we'll set per column
  • format() from date-fns converts to desired format
  • Display the formatted date

Why use cellProperties?

  • Allows different columns to display dates differently
  • One cell definition, multiple configurations

Optional error handling for production:

renderer: rendererFactory(({ td, value, cellProperties }) => {
  if (!value) {
    td.innerText = '';
    return;
  }
  try {
    td.innerText = format(new Date(value), cellProperties.renderFormat || 'MM/dd/yyyy');
  } catch (e) {
    td.innerText = 'Invalid date';
    td.style.color = 'red';
  }
})

Step 4: Create the Validator

validator: (value, callback) => {
  callback(isDate(new Date(value)));
}

What's happening:

  • Uses isDate from date-fns to validate the date
  • isDate checks if the value is a valid Date object
  • Returns true for valid dates, false for invalid ones

Alternative validation approaches:

// Using native JavaScript
validator: (value, callback) => {
  const date = new Date(value);

  callback(!isNaN(date.getTime()));
}

Step 5: Editor - Initialize (init)

Create the input element, initialize Flatpickr, and prepare the dark theme.

init(editor) {
  editor.input = editor.hot.rootDocument.createElement('INPUT') as HTMLInputElement;
  editor.input.classList.add('flatpickr-editor');

  editor.flatpickr = flatpickr(editor.input, {
    dateFormat: 'Y-m-d',
    onClose: () => {
      editor.finishEditing();
    },
  });

  editor.preventCloseElement = editor.flatpickr.calendarContainer;

  /**
   * Prepare dark theme stylesheet for dynamic loading.
   */
  editor._darkThemeLink = editor.hot.rootDocument.createElement('LINK') as HTMLLinkElement;
  editor._darkThemeLink.rel = 'stylesheet';
  editor._darkThemeLink.href = 'https://cdn.jsdelivr.net/npm/flatpickr/dist/themes/dark.css';
}

What's happening:

  1. Create an input element and add the flatpickr-editor CSS class for styling
  2. Initialize Flatpickr on the input with an onClose handler that calls finishEditing() when the calendar closes (e.g., after selecting a date or pressing Escape)
  3. Set preventCloseElement to the Flatpickr calendar container so that clicks inside the calendar are not treated as "outside" clicks — this keeps the editor open while the user selects a date
  4. Create a <link> element for the dark theme (loaded dynamically in afterOpen)

Key concepts:

The onClose handler

onClose: () => {
  editor.finishEditing();
},

When the user selects a date or closes the calendar (e.g., Escape), Flatpickr fires onClose. Calling finishEditing() saves the value and closes the editor.

The CSS class

editor.input.classList.add('flatpickr-editor');

Adds a CSS class to style the input element using Handsontable's CSS custom properties (tokens). See the CSS file for details.

The preventCloseElement pattern

Without it:

  1. User clicks cell to edit
  2. Flatpickr calendar opens
  3. User clicks on the calendar
  4. Handsontable treats the click as "outside" the editor and closes it

Solution: Assign the Flatpickr calendar container to editor.preventCloseElement. The editor factory treats this element as part of the editor, so clicks inside it do not close the editor prematurely.

Step 6: Editor - After Close Hook (afterClose)

Close the Flatpickr calendar when the editor is closed by non-Flatpickr means (e.g., Escape key or clicking outside).

afterClose(editor) {
  editor.flatpickr.close();
}

What's happening:

  • When the user closes the editor by pressing Escape or clicking outside the cell, Handsontable closes the editor but Flatpickr's calendar popup is not automatically closed
  • The afterClose hook runs when the editor is about to close; calling editor.flatpickr.close() ensures the calendar is hidden
  • Without this hook, the calendar would remain visible on screen after the editor has closed

Step 7: Editor - After Open Hook (afterOpen)

Toggle the dark theme when the editor opens, then open the Flatpickr calendar.

afterOpen(editor) {
  const isDark = editor.hot.rootDocument.documentElement.getAttribute('data-theme') === 'dark';
  const head = editor.hot.rootDocument.head;

  if (isDark && !editor._darkThemeLink.parentNode) {
    head.appendChild(editor._darkThemeLink);
  } else if (!isDark && editor._darkThemeLink.parentNode) {
    head.removeChild(editor._darkThemeLink);
  }

  editor.flatpickr.open();
}

What's happening:

  1. Check the current theme by reading the data-theme attribute on the <html> element
  2. Dynamically add or remove the Flatpickr dark theme stylesheet
  3. Call editor.flatpickr.open() to show the calendar (the editor factory does not open Flatpickr automatically)

Why dynamic theme loading?

  • Flatpickr themes are CSS files, not runtime APIs
  • Importing CSS directly (import 'flatpickr/dist/themes/dark.css') doesn't work in all build environments
  • Dynamic <link> injection allows toggling the theme each time the editor opens
  • The theme stylesheet is loaded from jsDelivr CDN and cached by the browser

Step 8: Editor - Before Open Hook (beforeOpen)

Apply per-column Flatpickr settings.

beforeOpen(editor, { cellProperties }) {
  for (const key in cellProperties.flatpickrSettings) {
    editor.flatpickr.set(key as keyof flatpickr.Options.Options, cellProperties.flatpickrSettings[key]);
  }
}

What's happening:

  1. Update Flatpickr settings from cellProperties.flatpickrSettings (e.g., locale, first day of week)
  2. The editor's value is set by the framework before beforeOpen runs

Key points:

  • beforeOpen is called before the editor opens
  • cellProperties.flatpickrSettings contains column-specific Flatpickr configuration
  • flatpickr.set() updates the existing Flatpickr instance with new settings

Why update settings in beforeOpen?

  • Allows different columns to have different Flatpickr configurations (e.g., EU vs US first day of week)
  • Settings are applied just before opening, ensuring they're fresh
  • More efficient than reinitializing Flatpickr each time

Step 9: Editor - Get Value (getValue)

Return the current date value from the input.

getValue(editor) {
  return editor.input.value;
}

What's happening:

  • Flatpickr automatically updates input.value in ISO format (e.g., "2025-03-15")
  • Simply return the input's current value
  • Called when Handsontable needs to save the cell value

Step 10: Editor - Set Value (setValue)

Initialize the editor with the cell's current date value.

setValue(editor, value) {
  editor.input.value = value;
  editor.flatpickr.setDate(value ? new Date(value) : new Date());
}

What's happening:

  • Set the input's value to the provided date string
  • Update Flatpickr's selected date using setDate() — use the cell value if present, otherwise the current date
  • This ensures Flatpickr displays the correct date when opened
  • Called to initialize the editor with the cell's current value

Step 11: Style the Editor with CSS

The editor input needs styling to match Handsontable's cell appearance. Create a CSS file using Handsontable's CSS custom properties (tokens):

.flatpickr-editor {
  width: 100%;
  height: 100%;
  box-sizing: border-box !important;
  border: none;
  border-radius: 0;
  outline: none;
  box-shadow: inset 0 0 0 var(--ht-cell-editor-border-width, 2px)
    var(--ht-cell-editor-border-color, #1a42e8),
    0 0 var(--ht-cell-editor-shadow-blur-radius, 0) 0
    var(--ht-cell-editor-shadow-color, transparent) !important;
  background-color: var(--ht-cell-editor-background-color, #ffffff) !important;
  padding: var(--ht-cell-vertical-padding, 4px)
    var(--ht-cell-horizontal-padding, 8px) !important;
  border: none !important;
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
}
.flatpickr-editor:focus-visible {
  border: none !important;
}

.flatpickr-editor.active {
  box-shadow: none;
  background-color: transparent;
  border-radius: 0 !important;
}

Why use CSS custom properties?

  • --ht-cell-editor-border-width and --ht-cell-editor-border-color match the default Handsontable editor border
  • --ht-cell-editor-background-color ensures the editor background matches the cell
  • --ht-cell-vertical-padding and --ht-cell-horizontal-padding align text with the cell content
  • These tokens automatically adapt when using custom Handsontable themes

The .active state: When the editor is active (calendar open), the input border and background are hidden since the calendar itself provides the visual feedback.

Step 12: Complete Cell Definition

TypeScript: Define an interface for the editor instance (optional in JavaScript):

interface FlatpickrEditorInstance {
  input: HTMLInputElement;
  flatpickr: flatpickr.Instance;
  preventCloseElement: HTMLElement;
  _darkThemeLink: HTMLLinkElement;
}

Put it all together:

const cellDefinition = {
  validator: (value, callback) => {
    callback(isDate(new Date(value)));
  },
  renderer: rendererFactory(({ td, value, cellProperties }) => {
    td.innerText = value ? format(new Date(value), cellProperties.renderFormat) : '';
  }),
  editor: editorFactory<FlatpickrEditorInstance>({
    init(editor) {
      editor.input = editor.hot.rootDocument.createElement('INPUT') as HTMLInputElement;
      editor.input.classList.add('flatpickr-editor');
      editor.flatpickr = flatpickr(editor.input, {
        dateFormat: 'Y-m-d',
        onClose: () => {
          editor.finishEditing();
        },
      });
      editor.preventCloseElement = editor.flatpickr.calendarContainer;
      editor._darkThemeLink = editor.hot.rootDocument.createElement('LINK') as HTMLLinkElement;
      editor._darkThemeLink.rel = 'stylesheet';
      editor._darkThemeLink.href = 'https://cdn.jsdelivr.net/npm/flatpickr/dist/themes/dark.css';
    },
    afterClose(editor) {
      editor.flatpickr.close();
    },
    afterOpen(editor) {
      const isDark = editor.hot.rootDocument.documentElement.getAttribute('data-theme') === 'dark';
      const head = editor.hot.rootDocument.head;
      if (isDark && !editor._darkThemeLink.parentNode) {
        head.appendChild(editor._darkThemeLink);
      } else if (!isDark && editor._darkThemeLink.parentNode) {
        head.removeChild(editor._darkThemeLink);
      }

      editor.flatpickr.open();
    },
    beforeOpen(editor, { cellProperties }) {
      for (const key in cellProperties.flatpickrSettings) {
        editor.flatpickr.set(key as keyof flatpickr.Options.Options, cellProperties.flatpickrSettings[key]);
      }
    },
    getValue(editor) {
      return editor.input.value;
    },
    setValue(editor, value) {
      editor.input.value = value;
      editor.flatpickr.setDate(value ? new Date(value) : new Date());
    },
  }),
};

What's happening:

  • validator: Ensures date is valid using isDate from date-fns
  • renderer: Displays formatted date using cellProperties.renderFormat (empty string for missing values)
  • editor: Uses editorFactory helper with:
    • init: Creates input, initializes Flatpickr with onClose calling finishEditing(), sets preventCloseElement so calendar clicks don't close the editor, prepares dark theme link
    • afterClose: Closes the Flatpickr calendar when the editor is closed by Escape or clicking outside
    • afterOpen: Toggles dark theme stylesheet and opens the Flatpickr calendar
    • beforeOpen: Applies per-column Flatpickr settings from cellProperties.flatpickrSettings
    • getValue: Returns the input's current value
    • setValue: Sets input value and Flatpickr's selected date

Note: The editorFactory helper handles container creation, positioning, and lifecycle management automatically.

Step 13: Use in Handsontable with Different Formats

const container = document.querySelector('#example1');

const hotOptions = {
  data,
  colHeaders: ['Product', 'Version', 'Release (EU)', 'Release (US)', 'Status'],
  autoRowSize: true,
  rowHeaders: true,
  height: 'auto',
  width: '100%',
  autoWrapRow: true,
  headerClassName: 'htLeft',
  columns: [
    { data: 'product', type: 'text', width: 200 },
    { data: 'version', type: 'text', width: 80 },
    {
      data: 'releaseDate',
      width: 130,
      allowInvalid: false,
      ...cellDefinition,
      renderFormat: DATE_FORMAT_EU,
      flatpickrSettings: {
        locale: {
          firstDayOfWeek: 1,
        },
      },
    },
    {
      data: 'releaseDate',
      width: 130,
      allowInvalid: false,
      ...cellDefinition,
      renderFormat: DATE_FORMAT_US,
      flatpickrSettings: {
        locale: {
          firstDayOfWeek: 0,
        },
      },
    },
    { data: 'status', type: 'text', width: 130 },
  ],
  licenseKey: 'non-commercial-and-evaluation',
};

const hot = new Handsontable(container, hotOptions);

TypeScript: Use const container = document.querySelector('#example1')! and type the options as Handsontable.GridSettings.

Key feature:

  • Same data column (releaseDate)
  • Two different display formats (EU vs US)
  • Two different calendar configurations (Monday vs Sunday first day)
  • One cell definition!

How It Works - Complete Flow

  1. Initial Load: Cell displays formatted date ("15/03/2025" EU or "03/15/2025" US), or empty string when there is no value
  2. User Double-Clicks or F2: Editor opens, container positioned over cell
  3. Before Open: beforeOpen applies per-column Flatpickr settings (e.g., first day of week)
  4. After Open: afterOpen toggles dark theme if needed and calls editor.flatpickr.open() to show the calendar
  5. Calendar Opens: Flatpickr displays the calendar with column-specific settings
  6. User Selects Date or Closes Calendar: onClose handler fires, calls finishEditing()
  7. Validation: Validator checks date is valid using isDate
  8. Save: Value saved in ISO format ("2025-03-15")
  9. Editor Closes: afterClose runs and closes the Flatpickr calendar (important when the user closed via Escape or clicking outside). Container hidden, cell renderer displays the new formatted date

Advanced Enhancements

1. Time Picker

Add time selection:

flatpickrSettings: {
  enableTime: true,
  dateFormat: 'Y-m-d H:i',
  time_24hr: true
}

// Update renderer
renderFormat: 'dd/MM/yyyy HH:mm'

2. Date Range Restrictions

Limit selectable dates:

flatpickrSettings: {
  minDate: '2024-01-01',
  maxDate: '2024-12-31',
  disable: [
    // Disable weekends
    function(date) {
      return (date.getDay() === 0 || date.getDay() === 6);
    }
  ]
}

3. Inline Calendar

Show calendar always visible:

flatpickrSettings: {
  inline: true,
  static: true
}

// Adjust wrapper height in open()
editor.container.style.height = '300px';

4. Multiple Date Locales

Use Flatpickr locales:

import { French } from 'flatpickr/dist/l10n/fr.js';

flatpickrSettings: {
  locale: French,
  dateFormat: 'd/m/Y'
}

5. Custom Date Ranges

Add shortcuts:

// Requires flatpickr shortcutButtonsPlugin
import ShortcutButtonsPlugin from 'flatpickr/dist/plugins/shortcutButtons/shortcutButtons.js';

flatpickrSettings: {
  plugins: [
    ShortcutButtonsPlugin({
      button: [
        { label: 'Today' },
        { label: 'Next Week' },
      ],
      onClick: (index, fp) => {
        let date;

        if (index === 0) {
          date = new Date();

        } else if (index === 1) {
          date = new Date();
          date.setDate(date.getDate() + 7);
        }

        fp.setDate(date);
      }
    })
  ]
}

Congratulations! You've created a production-ready date picker with full localization support, dark theme toggling, and advanced configuration.