Callbacks

note

All Module callbacks are available in this class.

in

Fires when an element enters the viewport. The callback receives the element and the direction from which it appeared.

Callback Arguments:

• element - The DOM element that entered the viewport
• direction - The direction from which the element entered: 'fromBottom', 'fromTop', 'fromLeft', or 'fromRight'

const observer = new InView({
  onIn: ({ element, direction }) => {
    console.log(element, 'entered viewport from', direction);

    // Use direction for conditional logic
    if (direction === 'fromBottom') {
      // Animate from bottom
    } else if (direction === 'fromTop') {
      // Animate from top
    }
  },
});

or using the event listener pattern:

const destruct = observer.on('in', ({ element, direction }) => {
  console.log(element, 'entered viewport from', direction);
});

// Cancel the callback
destruct();

out

Fires when an element leaves the viewport. The callback receives the element and the direction from which it disappeared.

Callback Arguments:

• element - The DOM element that left the viewport
• direction - The direction from which the element left: 'fromBottom', 'fromTop', 'fromLeft', or 'fromRight'

note

The out callback only fires if hasOut: true (default). Set hasOut: false to disable out events for better performance when you only need one-time triggers.

const observer = new InView({
  onOut: ({ element, direction }) => {
    console.log(element, 'left viewport from', direction);
  },
});

or using the event listener pattern:

const destruct = observer.on('out', ({ element, direction }) => {
  console.log(element, 'left viewport from', direction);
});

// Cancel the callback
destruct();