Custom Modifiers

Draft

This documentation is still a work in progress. If you have any questions, ask to the discussions page on Github.

Modifiers

In DayPicker, a modifier is added to a day when the day matches a specific condition, called Matcher. For example, selected days have the selected modifiers, disabled days the disabled modifier, the today's date matches the today modifier, etc.

<DayPicker selected={new Date()} />
<DayPicker disabled={new Date()} />
<DayPicker hidden={new Date()} />

Understanding Modifiers

• Use modifiers to change the appearance of the days in the calendar or to inspect the days the user has interacted with (e.g. picking a day)
• DayPicker comes with some pre-built modifiers, such as disabled, selected, hidden, today, range_start, etc. designed to cover the most common use cases. See the InternalModifiers for a list of the internal modifiers.
• It is possible to implement custom modifiers, extending the behavior of DayPicker: see Custom Modifiers below for more details.

The selected Modifier

<DayPicker selected={new Date()} />

When in selection mode, use the selected prop to add the selected modifier to the selected dates, and style them accordingly. To see how to implement the selected modifier, see the Selecting days guide.

Disabling Days

Use the disabled modifier to disable one or more days. Pass a Matcher or an array of Matchers to choose the disabled days:

// Disable Sundays and Saturdays
<DayPicker disabled={{ dayOfWeek: [0, 6] }} />

Hidden days

The hidden modifier removes the day from the calendar. Set the hidden days using the hidden prop.

const hiddenDays = [
  new Date(2022, 5, 10),
  new Date(2022, 5, 20),
  new Date(2022, 5, 11)
];

<DayPicker defaultMonth={hiddenDays[0]} hidden={hiddenDays} />;

The today Modifier

The today modifier is added to the current date:

function ModifiersToday() {
  const initialFooter = <p>Try clicking the today’s date.</p>;
  const [footer, setFooter] = useState(initialFooter);

  const handleDayClick: DayMouseEventHandler = (day, modifiers) => {
    if (modifiers.today) {
      setFooter(<p>You clicked the today’s date.</p>);
    } else {
      setFooter(initialFooter);
    }
  };
  return <DayPicker onDayClick={handleDayClick} footer={footer} />;
}

info

You can change the current date using the today prop.

Custom Modifiers

Add new modifiers according to your app’s requirements. For example, a booking app may use a booked modifier to mark days as already booked.

Use the modifiers prop to pass an object with custom modifiers and their matcher. Change the inline-style of the cell with modifiersStyles or with modifiersClassNames.

const bookedDays = [
  new Date(2024, 5, 8),
  new Date(2024, 5, 9),
  new Date(2024, 5, 10),
  { from: new Date(2024, 5, 15), to: new Date(2024, 5, 20) }
];
export function ModifiersCustom() {
  const handleDayClick: DayMouseEventHandler = (day, { booked }) => {
    alert(`Day ${day.toLocaleDateString()} is booked? ` + booked);
  };

  return (
    <DayPicker
      defaultMonth={new Date(2024, 5)}
      modifiers={{ booked: bookedDays }}
      modifiersClassNames={{ booked: "booked" }}
      onDayClick={handleDayClick}
    />
  );
}

.booked {
  position: relative;
}
/* Strikeout */
.booked::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 0;
  right: 0;
  height: 2px;
  background: currentColor;
  z-index: 1;
  transform: rotate(-45deg);
}

Styling Modifiers

A day can be styled according to its modifiers – using CSS or inline styles. See Styling DayPicker for more details.