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Simplify isIntersecting in status_list.js (#3371)

This commit is contained in:
Nolan Lawson 2017-05-28 07:26:35 -07:00 committed by Eugen Rochko
parent 189a06d2a2
commit 28cbfb9f10
1 changed files with 22 additions and 5 deletions
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27
app/javascript/mastodon/components/status_list.js
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@ -27,7 +27,8 @@ class StatusList extends ImmutablePureComponent {
}; };
state = { state = {
isIntersecting: [{ }], isIntersecting: {},
intersectionCount: 0,
} }
statusRefQueue = [] statusRefQueue = []
@ -65,15 +66,31 @@ class StatusList extends ImmutablePureComponent {
attachIntersectionObserver () { attachIntersectionObserver () {
const onIntersection = (entries) => { const onIntersection = (entries) => {
this.setState(state => { this.setState(state => {
const isIntersecting = { };
entries.forEach(entry => { entries.forEach(entry => {
const statusId = entry.target.getAttribute('data-id'); const statusId = entry.target.getAttribute('data-id');
state.isIntersecting[0][statusId] = entry.isIntersecting; state.isIntersecting[statusId] = entry.isIntersecting;
}); });
return { isIntersecting: [state.isIntersecting[0]] }; // isIntersecting is a map of DOM data-id's to booleans (true for
// intersecting, false for non-intersecting).
//
// We always want to return true in shouldComponentUpdate() if
// this object changes, because onIntersection() is only called if
// something has changed.
//
// Now, we *could* use an immutable map or some other structure to
// diff the full map, but that would be pointless because the browser
// has already informed us that something has changed. So we can just
// use a regular object, which will be diffed by ImmutablePureComponent
// based on reference equality (i.e. it's always "unchanged") and
// then we just increment intersectionCount to force a change.
return {
isIntersecting: state.isIntersecting,
intersectionCount: state.intersectionCount + 1,
};
}); });
}; };
@ -122,7 +139,7 @@ class StatusList extends ImmutablePureComponent {
render () { render () {
const { statusIds, onScrollToBottom, scrollKey, shouldUpdateScroll, isLoading, isUnread, hasMore, prepend, emptyMessage } = this.props; const { statusIds, onScrollToBottom, scrollKey, shouldUpdateScroll, isLoading, isUnread, hasMore, prepend, emptyMessage } = this.props;
const isIntersecting = this.state.isIntersecting[0]; const { isIntersecting } = this.state;
let loadMore = null; let loadMore = null;
let scrollableArea = null; let scrollableArea = null;