inView

The inView gesture triggers when an element enters and leaves the window's viewport, or the viewport of a scrollable parent element.

inView("#carousel li", (info) => {
  animate(info.target, { opacity: 1 })
})

Detecting when an element is in view can help creating effects like:

• Animating elements in when they scroll into view.
• Deactivating animations when they're no longer visible.
• Lazy-loading content.
• Automatically start/stop videos.

Motion One's inView function is built on the browser's native Intersection Observer API for the best possible performance (all calculations happen off the main JavaScript thread) and a tiny filesize (just 0.5kb).

Usage

Import from "motion":

import { inView } from "motion"

inView can accept either a selector, Element, or array of Elements.

// Selector
inView("section", callback)

// Element
const box = document.getElementById("box")
inView(box, callback)

By default, the provided callback will fire just once, when the element first enters the viewport.

inView(element, () => {
  console.log("Element has entered the viewport")
})

This callback is provided an IntersectionObserverEntry object which contains information on the intersection.

inView("a", (info) => {
  console.log("The link  ", info.target.id, " has entered the viewport")
})

Leaving the viewport

A function returned from this callback will fire when the element leaves the viewport.

inView(element, (info) => {
  const controls = animate(info.target, { opacity: 1 })

  // This will fire when the element leaves the viewport
  return (leaveInfo) => controls.stop()
})

Additionally, the gesture will also continue to fire as the element enters/leaves the viewport.

Detect a scrollable element

By default, inView detects when the provided element(s) enter/leave the default viewport: The browser window.

But it can also detect when the element(s) enter/leave the viewport of a scrollable parent element, by passing that element to the root option:

const carousel = document.querySelector("#carousel")

inView("#carousel li", callback, { root: carousel })

Stop gesture

inView returns a function that, when fired, will stop gesture detection.

const stop = inView(element, callback)

stop()

Options

root

Default: window

If provided, inView will use the root element's viewport to detect whether the target elements are in view. Otherwise defaults to the browser window.

const carousel = document.querySelector("#carousel")

inView("#carousel li", callback, { root: carousel })

margin

Default: "0"

A CSS margin to apply to the root viewport so an element can be considered in view sooner or later.

Can be in pixels or percentages. It can accept up to four values in the order of top/right/bottom/left.

inView(element, callback, { margin: "0px 100px 0px 0px" })

Positive values extend the viewport boundaries beyond the root whereas negative values will pull it in.

Note: For browser security reasons, margin won't take affect within cross-origin iframes unless root is explicitly defined.

amount

Default: "any"

The amount of the target element that needs to be within the viewport boundaries to be considered in view.

This can be defined as "any", for any of the element, or "all", for all of the element.

Additionally, it can be defined as a number proportion between 0 and 1 where 0 is "any" and 1 is "all".

Examples

Scroll-triggered animations

import { inView, animate } from "motion";

inView("section", ({ target }) => {
  animate(
    target.querySelector("span"),
    { opacity: 1, transform: "none" },
    { delay: 0.2, duration: 0.9, easing: [0.17, 0.55, 0.55, 1] }
  );
});