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scrollParent.ts
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scrollParent.ts
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/* eslint-disable no-cond-assign, no-continue */
import css from './css'
import height from './height'
import isDocument from './isDocument'
/**
* Find the first scrollable parent of an element.
*
* @param element Starting element
* @param firstPossible Stop at the first scrollable parent, even if it's not currently scrollable
*/
export default function scrollParent(
element: HTMLElement,
firstPossible?: boolean
) {
const position = css(element, 'position')
const excludeStatic = position === 'absolute'
const ownerDoc = element.ownerDocument
if (position === 'fixed') return ownerDoc || document
// @ts-ignore
while ((element = element.parentNode) && !isDocument(element)) {
const isStatic = excludeStatic && css(element, 'position') === 'static'
const style =
(css(element, 'overflow') || '') +
(css(element, 'overflow-y') || '') +
css(element, 'overflow-x')
if (isStatic) continue
if (
/(auto|scroll)/.test(style) &&
(firstPossible || height(element) < element!.scrollHeight)
) {
return element
}
}
return ownerDoc || document
}