133 lines
7.0 KiB
Markdown
133 lines
7.0 KiB
Markdown
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[](https://circleci.com/gh/stipsan/compute-scroll-into-view)
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[](https://npm-stat.com/charts.html?package=compute-scroll-into-view)
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[](https://www.npmjs.com/package/compute-scroll-into-view)
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[![gzip size][gzip-badge]][unpkg-dist]
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[![size][size-badge]][unpkg-dist]
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[![module formats: umd, cjs, and es][module-formats-badge]][unpkg-dist]
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[](https://github.com/semantic-release/semantic-release)
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Lower level API that is used by the [ponyfill](https://ponyfill.com) [scroll-into-view-if-needed](https://github.com/stipsan/scroll-into-view-if-needed) to compute where (if needed) elements should scroll based on [options defined in the spec](https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView) and the [`scrollMode: "if-needed"` draft spec proposal](https://github.com/w3c/csswg-drafts/pull/1805).
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Use this if you want the smallest possible bundlesize and is ok with implementing the actual scrolling yourself.
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Scrolling SVG elements are supported, as well as Shadow DOM elements. The [VisualViewport](https://developer.mozilla.org/en-US/docs/Web/API/VisualViewport) API is also supported, ensuring scrolling works properly on modern devices. Quirksmode is also supported as long as you polyfill [`document.scrollingElement`](https://developer.mozilla.org/en-US/docs/Web/API/document/scrollingElement).
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## Install
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```bash
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yarn add compute-scroll-into-view
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```
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The UMD build is also available on [unpkg](https://unpkg.com/compute-scroll-into-view/umd/):
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```html
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<script src="https://unpkg.com/compute-scroll-into-view/umd/compute-scroll-into-view.min.js"></script>
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```
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You can find the library on `window.computeScrollIntoView`.
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## Usage
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```js
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// es6 import
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import computeScrollIntoView from 'compute-scroll-into-view'
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// or es5
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const computeScrollIntoView = require('compute-scroll-into-view')
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const node = document.getElementById('hero')
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// same behavior as Element.scrollIntoView({block: "nearest", inline: "nearest"})
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// see: https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
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const actions = computeScrollIntoView(node, {
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scrollMode: 'if-needed',
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block: 'nearest',
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inline: 'nearest',
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})
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// same behavior as Element.scrollIntoViewIfNeeded(true)
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// see: https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoViewIfNeeded
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const actions = computeScrollIntoView(node, { scrollMode: 'if-needed' block: 'center', inline: 'center' })
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// Then perform the scrolling, use scroll-into-view-if-needed if you don't want to implement this part
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actions.forEach(({ el, top, left }) => {
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el.scrollTop = top
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el.scrollLeft = left
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})
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```
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## API
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### computeScrollIntoView(target, options)
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### options
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Type: `Object`
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#### [block](https://scroll-into-view-if-needed.netlify.com/#scroll-alignment)
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Type: `'start' | 'center' | 'end' | 'nearest'`<br> Default: `'center'`
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Control the logical scroll position on the y-axis. The spec states that the `block` direction is related to the [writing-mode](https://developer.mozilla.org/en-US/docs/Web/CSS/writing-mode), but this is not implemented yet in this library.
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This means that `block: 'start'` aligns to the top edge and `block: 'end'` to the bottom.
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#### [inline](https://scroll-into-view-if-needed.netlify.com/#scroll-alignment)
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Type: `'start' | 'center' | 'end' | 'nearest'`<br> Default: `'nearest'`
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Like `block` this is affected by the [writing-mode](https://developer.mozilla.org/en-US/docs/Web/CSS/writing-mode). In left-to-right pages `inline: 'start'` will align to the left edge. In right-to-left it should be flipped. This will be supported in a future release.
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#### [scrollMode](https://scroll-into-view-if-needed.netlify.com/#scrolling-if-needed)
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Type: `'always' | 'if-needed'`<br> Default: `'always'`
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This is a proposed addition to the spec that you can track here: https://github.com/w3c/csswg-drafts/pull/1805
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This library will be updated to reflect any changes to the spec and will provide a migration path.
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To be backwards compatible with `Element.scrollIntoViewIfNeeded` if something is not 100% visible it will count as "needs scrolling". If you need a different visibility ratio your best option would be to implement an [Intersection Observer](https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API).
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#### [boundary](https://scroll-into-view-if-needed.netlify.com/#limit-propagation)
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Type: `Element | Function`
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By default there is no boundary. All the parent elements of your target is checked until it reaches the viewport ([`document.scrollingElement`](https://developer.mozilla.org/en-US/docs/Web/API/document/scrollingElement)) when calculating layout and what to scroll.
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By passing a boundary you can short-circuit this loop depending on your needs:
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- Prevent the browser window from scrolling.
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- Scroll elements into view in a list, without scrolling container elements.
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You can also pass a function to do more dynamic checks to override the scroll scoping:
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```js
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const actions = computeScrollIntoView(target, {
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boundary: parent => {
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// By default `overflow: hidden` elements are allowed, only `overflow: visible | clip` is skipped as
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// this is required by the CSSOM spec
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if (getComputedStyle(parent)['overflow'] === 'hidden') {
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return false
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}
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return true
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},
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})
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```
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#### skipOverflowHiddenElements
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Type: `Boolean`<br> Default: `false`
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By default the [spec](https://drafts.csswg.org/cssom-view/#scrolling-box) states that `overflow: hidden` elements should be scrollable because it has [been used to allow programatic scrolling](https://drafts.csswg.org/css-overflow-3/#valdef-overflow-hidden). This behavior can sometimes lead to [scrolling issues](https://github.com/stipsan/scroll-into-view-if-needed/pull/225#issue-186419520) when you have a node that is a child of an `overflow: hidden` node.
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This package follows the convention [adopted by Firefox](https://hg.mozilla.org/integration/fx-team/rev/c48c3ec05012#l7.18) of setting a boolean option to _not_ scroll all nodes with `overflow: hidden` set.
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# TypeScript support
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This library ships with library definitions for TypeScript.
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> FlowType definitions is coming soon...
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[gzip-badge]: http://img.badgesize.io/https://unpkg.com/compute-scroll-into-view/umd/compute-scroll-into-view.min.js?compression=gzip&label=gzip%20size&style=flat-square
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[size-badge]: http://img.badgesize.io/https://unpkg.com/compute-scroll-into-view/umd/compute-scroll-into-view.min.js?label=size&style=flat-square
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[unpkg-dist]: https://unpkg.com/compute-scroll-into-view/umd/
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[module-formats-badge]: https://img.shields.io/badge/module%20formats-umd%2C%20cjs%2C%20es-green.svg?style=flat-square
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