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author | beatrix <beatrix.bitrot@gmail.com> | 2017-12-06 17:44:07 -0500 |
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committer | GitHub <noreply@github.com> | 2017-12-06 17:44:07 -0500 |
commit | 81b01457598459c42a7b14d9aa14f91ba60dcae1 (patch) | |
tree | 7d3e6dadb75f3be95e5a5ed8b7ecfe90e7711831 /app/javascript/flavours/glitch/util/intersection_observer_wrapper.js | |
parent | f1cbea77a4a52929244198dcbde26d63d837489a (diff) | |
parent | 017fc81caf8f265e5c5543186877437485625795 (diff) |
Merge pull request #229 from glitch-soc/glitch-theme
Advanced Next-Level Flavours And Skins For Mastodon™
Diffstat (limited to 'app/javascript/flavours/glitch/util/intersection_observer_wrapper.js')
-rw-r--r-- | app/javascript/flavours/glitch/util/intersection_observer_wrapper.js | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/app/javascript/flavours/glitch/util/intersection_observer_wrapper.js b/app/javascript/flavours/glitch/util/intersection_observer_wrapper.js new file mode 100644 index 000000000..2b24c6583 --- /dev/null +++ b/app/javascript/flavours/glitch/util/intersection_observer_wrapper.js @@ -0,0 +1,57 @@ +// Wrapper for IntersectionObserver in order to make working with it +// a bit easier. We also follow this performance advice: +// "If you need to observe multiple elements, it is both possible and +// advised to observe multiple elements using the same IntersectionObserver +// instance by calling observe() multiple times." +// https://developers.google.com/web/updates/2016/04/intersectionobserver + +class IntersectionObserverWrapper { + + callbacks = {}; + observerBacklog = []; + observer = null; + + connect (options) { + const onIntersection = (entries) => { + entries.forEach(entry => { + const id = entry.target.getAttribute('data-id'); + if (this.callbacks[id]) { + this.callbacks[id](entry); + } + }); + }; + + this.observer = new IntersectionObserver(onIntersection, options); + this.observerBacklog.forEach(([ id, node, callback ]) => { + this.observe(id, node, callback); + }); + this.observerBacklog = null; + } + + observe (id, node, callback) { + if (!this.observer) { + this.observerBacklog.push([ id, node, callback ]); + } else { + this.callbacks[id] = callback; + this.observer.observe(node); + } + } + + unobserve (id, node) { + if (this.observer) { + delete this.callbacks[id]; + this.observer.unobserve(node); + } + } + + disconnect () { + if (this.observer) { + this.callbacks = {}; + this.observer.disconnect(); + this.observer = null; + } + } + +} + +export default IntersectionObserverWrapper; |