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fix: add scrollable area check and scrollable area attribute #8723

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teemingc wants to merge 3 commits into from
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fix: add scrollable area check and scrollable area attribute #8723

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3ac0d72
add scrollable area check and custom attribute
teemingc Jan 25, 2023
7229d16
revert removal of unused hash param type
teemingc Jan 25, 2023
a8669e7
move querySelectorAll into dev check
teemingc Jan 25, 2023
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63 changes: 60 additions & 3 deletions packages/kit/src/runtime/client/client.js
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,63 @@ function update_scroll_positions(index) {
scroll_positions[index] = scroll_state();
}

/** @param {Element} element */
function is_scrollable(element) {
const style = getComputedStyle(element);
return style.display !== 'contents' &&
(style.overflowY === 'auto' || style.overflowY === 'scroll') &&
element.scrollHeight > element.clientHeight
? element
: null;
}

const SCROLLABLE_AREA_ATTRIBUTE = 'data-sveltekit-main-scrollable';

function get_scrollable_area() {
const is_default_scrollable = getComputedStyle(document.documentElement).overflowY !== 'hidden';
const scrollable_area = is_default_scrollable
? document.documentElement
: is_scrollable(document.body);

const custom_scrollable_area = document.querySelector(`*[${SCROLLABLE_AREA_ATTRIBUTE}]`);

if (DEV) {
if (scrollable_area && custom_scrollable_area) {
console.warn(
`<${scrollable_area.tagName.toLowerCase()}> is already scrollable but '${SCROLLABLE_AREA_ATTRIBUTE}' was found on an element. Only use '${SCROLLABLE_AREA_ATTRIBUTE}' if <html> or <body> are not the main scrollable areas`,
custom_scrollable_area
);
} else if (custom_scrollable_area && !is_scrollable(custom_scrollable_area)) {
console.error(
`Invalid main scrollable area. Ensure that the overflow style is set to 'auto' or 'scroll', and the element height is less than its content`,
custom_scrollable_area
);
} else if (!scrollable_area && !custom_scrollable_area) {
throw new Error(
`No scrollable area found. Identify the main scrolling area with '${SCROLLABLE_AREA_ATTRIBUTE}' to ensure navigation functions correctly`
);
}

const custom_scrollable_areas = document.querySelectorAll(`*[${SCROLLABLE_AREA_ATTRIBUTE}]`);
if (custom_scrollable_areas.length > 1) {
console.warn(
`More than one '${SCROLLABLE_AREA_ATTRIBUTE}' found. Only one main scrolling area is allowed`,
custom_scrollable_areas
);
}
}

return scrollable_area ?? custom_scrollable_area;
}

/***
* @param {number} x
* @param {number} y
*/
function scroll_to(x, y) {
get_scrollable_area()?.scrollTo(x, y);
}

/**
* @param {{
* target: HTMLElement;
Expand Down Expand Up @@ -128,7 +185,7 @@ export function create_client({ target, base }) {
const scroll = scroll_positions[current_history_index];
if (scroll) {
history.scrollRestoration = 'manual';
scrollTo(scroll.x, scroll.y);
scroll_to(scroll.x, scroll.y);
}

/** @type {import('types').Page} */
Expand Down Expand Up @@ -345,14 +402,14 @@ export function create_client({ target, base }) {
if (autoscroll) {
const deep_linked = url.hash && document.getElementById(url.hash.slice(1));
if (scroll) {
scrollTo(scroll.x, scroll.y);
scroll_to(scroll.x, scroll.y);
} else if (deep_linked) {
// Here we use `scrollIntoView` on the element instead of `scrollTo`
// because it natively supports the `scroll-margin` and `scroll-behavior`
// CSS properties.
deep_linked.scrollIntoView();
} else {
scrollTo(0, 0);
scroll_to(0, 0);
}
}
} else {
Expand Down