Cell Hover Highlight

Highlight the resource row and date column on cell hover to improve usability by clearly showing where the user is interacting.

This is achieved using the onCellHoverIn and onCellHoverOut lifecycle events. These track the hovered cell and update the resources with a custom cssClass, which highlights the resource row. A popup is also shown on hover, displaying relevant information about the cell like the date and resource name.

The column highlight is applied using the renderCell, renderSidebar, renderTimelineDay, and renderDayFooter callbacks, where conditional markup is returned to highlight the vertical column.

This makes it easy to implement custom hover interactions that match your design and UX goals.

Get started with this example

Demo

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Add row and column hover highlighting to a resource timeline — highlight the active resource row and date column on hover.

Code

View code on GitHub 
import { Eventcalendar, formatDate, Popup, setOptions } from '@mobiscroll/react';
import { useCallback, useMemo, useState } from 'react';

setOptions({
  locale:  ,
  theme: ' ',
  themeVariant: ' '
});

function App() {
  const [hoverDate, setHoverDate] = useState(null);
  const [hoverResource, setHoverResource] = useState(null);
  const [anchor, setAnchor] = useState(null);
  const [isPopupOpen, setPopupOpen] = useState(false);

  const myView = useMemo(
    () => ({
      timeline: {
        type: 'month',
        resolutionHorizontal: 'day',
      },
    }),
    [],
  );

  const myEvents = useMemo(
    () => [
      { start: '2026-10-02T00:00', end: '2026-10-05T00:00', title: 'Event 1', resource: 1 },
      { start: '2026-10-10T09:00', end: '2026-10-15T15:00', title: 'Event 2', resource: 3 },
      { start: '2026-10-12T00:00', end: '2026-10-14T00:00', title: 'Event 3', resource: 4 },
      { start: '2026-10-15T07:00', end: '2026-10-20T12:00', title: 'Event 4', resource: 5 },
      { start: '2026-10-03T00:00', end: '2026-10-10T00:00', title: 'Event 5', resource: 6 },
      { start: '2026-10-10T08:00', end: '2026-10-11T20:00', title: 'Event 6', resource: 7 },
      { start: '2026-10-22T00:00', end: '2026-10-28T00:00', title: 'Event 7', resource: 7 },
      { start: '2026-10-08T00:00', end: '2026-10-13T00:00', title: 'Event 8', resource: 15 },
      { start: '2026-10-25T00:00', end: '2026-10-27T00:00', title: 'Event 9', resource: 10 },
      { start: '2026-10-20T00:00', end: '2026-10-23T00:00', title: 'Event 10', resource: 12 },
    ],
    [],
  );

  const [myResources, setResources] = useState([
    { id: 1, name: 'Resource A', color: '#e20000' },
    { id: 2, name: 'Resource B', color: '#76e083' },
    { id: 3, name: 'Resource C', color: '#4981d6' },
    { id: 4, name: 'Resource D', color: '#e25dd2' },
    { id: 5, name: 'Resource E', color: '#1dab2f' },
    { id: 6, name: 'Resource F', color: '#d6d145' },
    { id: 7, name: 'Resource G', color: '#34c8e0' },
    { id: 8, name: 'Resource H', color: '#9dde46' },
    { id: 9, name: 'Resource I', color: '#166f6f' },
    { id: 10, name: 'Resource J', color: '#f7961e' },
    { id: 11, name: 'Resource K', color: '#34c8e0' },
    { id: 12, name: 'Resource L', color: '#af0000' },
    { id: 13, name: 'Resource M', color: '#446f1c' },
    { id: 14, name: 'Resource N', color: '#073138' },
    { id: 15, name: 'Resource O', color: '#4caf00' },
  ]);

  const handleCellHoverIn = useCallback((args) => {
    setResources((prevResources) => {
      const updated = prevResources.map((r) => ({
        ...r,
        cssClass: r.id === args.resource.id ? 'mds-highlight-row-hover' : '',
      }));
      setHoverResource(updated.find((r) => r.id === args.resource.id));
      return updated;
    });

    setHoverDate(args.date);
    setAnchor(args.domEvent.target);
    setPopupOpen(true);
  }, []);

  const handleCellHoverOut = useCallback(() => {
    setHoverDate(null);
    setHoverResource(null);
    setResources((prevResources) => prevResources.map((r) => ({ ...r, cssClass: '' })));
    setPopupOpen(false);
  }, []);

  const renderCell = useCallback(
    (args) => {
      const isHover = hoverDate && args.date.getTime() === hoverDate.getTime();
      return isHover ? <div className="mds-highlight-col-hover" /> : null;
    },
    [hoverDate],
  );

  const renderSidebar = useCallback((resource) => <div>{resource.name} Sidebar</div>, []);

  const renderTimelineDay = useCallback(
    (day) => {
      const isHover = hoverDate && day.date.getTime() === hoverDate.getTime();
      const hoverClass = isHover ? ' mds-highlight-col-hover' : '';
      return <div className={'mds-highlight-day-content' + hoverClass}>{formatDate('D DDD', day.date)}</div>;
    },
    [hoverDate],
  );

  const renderDayFooter = useCallback(
    (day) => {
      const isHover = hoverDate && day.date.getTime() === hoverDate.getTime();
      const hoverClass = isHover ? ' mds-highlight-col-hover' : '';
      return <div className={'mds-highlight-day-content' + hoverClass}>{formatDate('D DDD', day.date)}</div>;
    },
    [hoverDate],
  );

  return (
    <>
      <Eventcalendar
        cssClass="mds-highlight-hover"
        data={myEvents}
        resources={myResources}
        renderCell={renderCell}
        renderSidebar={renderSidebar}
        renderTimelineDay={renderTimelineDay}
        renderDayFooter={renderDayFooter}
        onCellHoverIn={handleCellHoverIn}
        onCellHoverOut={handleCellHoverOut}
        view={myView}
      />
      <Popup
        anchor={anchor}
        closeOnScroll={true}
        display="anchored"
        focusOnClose={false}
        isOpen={isPopupOpen}
        scrollLock={false}
        showOverlay={false}
      >
        {hoverResource && hoverDate && (
          <div className="mds-highlight-tooltip">
            <div className="mds-highlight-tooltip-name">{hoverResource.name}</div>
            <div className="mds-highlight-tooltip-date">{formatDate('MMM DD, YYYY', hoverDate)}</div>
          </div>
        )}
      </Popup>
    </>
  );
}

export default App;

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