smooth-scroll-into-view-if-needed

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!smooth-scroll-into-view-if-needed

This is an addon to scroll-into-view-if-needed that ponyfills smooth scrolling.
And while scroll-into-view-if-needed use the same default options as browsers and the spec does, this library is a bit more opinionated and include bonus features that help you build great UIs.

Demo

Install

``bash
yarn add smooth-scroll-into-view-if-needed
`

The UMD build is also available on unpkg:

`html

`

You can find the library on window.scrollIntoView.

Usage

`js
import scrollIntoView from 'smooth-scroll-into-view-if-needed'
const node = document.getElementById('hero')

// options.behavior is set to smooth by default so you don't have to pass options like in scroll-into-view-if-needed
scrollIntoView(node)

// combine it with any of the other options from 'scroll-into-view-if-needed'
scrollIntoView(node, {
scrollMode: 'if-needed',
block: 'nearest',
inline: 'nearest',
})

// a promise is always returned to help reduce boilerplate
const sequence = async () => {
const slide = document.getElementById('slide-3')
// First smooth scroll to hero
await scrollIntoView(node, { behavior: 'smooth' })
// Then we scroll to a slide in a slideshow
return scrollIntoView(slide, { behavior: 'smooth' })
}
`

Polyfills

This library rely on Promise and requestAnimationFrame. This library does not ship with polyfills for these to keep bundlesizes as low as possible.

API

Check the full API in scroll-into-view-if-needed.

$3

scroll-into-view-if-needed does not return anything, while this library will return a Promise that is resolved when all of the scrolling boxes are finished scrolling.

> The ability to cancel animations will be added in a future version.

$3

Type: Object

#### behavior

Type: 'auto' | 'smooth' | Function
Default: 'smooth'

This option deviates from scroll-into-view-if-needed in two ways.

- The default value is smooth instead of auto
- Using smooth adds it to browsers that miss it, and overrides the native smooth scrolling in the browsers that have it to ensure the scrolling is consistent in any browser.

The options auto or Function behaves exactly like in scroll-into-view-if-needed.

#### duration

Type: number
Default: 300

> Introduced in v1.1.0

This setting is not a hard limit.
The duration of a scroll differs depending on how many elements is scrolled, and the capabilities of the browser.
On mobile the browser might pause or throttle the animation if the user switches to another tab.
And there might be nothing to scroll.
No matter the scenario a Promise is returned so you can await on it.

#### ease

Type: Function

> Introduced in v1.1.0

The default easing is easeOutQuint based on these algorithms: https://gist.github.com/gre/1650294#file-easing-js

Linear example:

`typescript
scrollIntoView(node, {
ease: (t) => t,
})
`

Acceleration until halfway, then deceleration:

`typescript
scrollIntoView(node, {
ease: (t) =>
t < 0.5 ? 4 t t t : (t - 1) (2 t - 2) (2 * t - 2) + 1,
})
`

Sine easing in and out:

`typescript
scrollIntoView(node, {
ease: (t) => (1 + Math.sin(Math.PI * t - Math.PI / 2)) / 2,
})
``

Credits

- smoothscroll for the reference implementation of smooth scrolling.

More documentation will be added

[gzip-badge]: http://img.badgesize.io/https://unpkg.com/smooth-scroll-into-view-if-needed/umd/smooth-scroll-into-view-if-needed.min.js?compression=gzip&label=gzip%20size&style=flat-square
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[unpkg-dist]: https://unpkg.com/smooth-scroll-into-view-if-needed/umd/
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