58 lines
1.5 KiB
JavaScript
58 lines
1.5 KiB
JavaScript
// Wrapper for IntersectionObserver in order to make working with it
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// a bit easier. We also follow this performance advice:
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// "If you need to observe multiple elements, it is both possible and
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// advised to observe multiple elements using the same IntersectionObserver
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// instance by calling observe() multiple times."
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// https://developers.google.com/web/updates/2016/04/intersectionobserver
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class IntersectionObserverWrapper {
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callbacks = {};
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observerBacklog = [];
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observer = null;
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connect (options) {
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const onIntersection = (entries) => {
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entries.forEach(entry => {
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const id = entry.target.getAttribute('data-id');
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if (this.callbacks[id]) {
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this.callbacks[id](entry);
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}
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});
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};
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this.observer = new IntersectionObserver(onIntersection, options);
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this.observerBacklog.forEach(([ id, node, callback ]) => {
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this.observe(id, node, callback);
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});
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this.observerBacklog = null;
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}
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observe (id, node, callback) {
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if (!this.observer) {
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this.observerBacklog.push([ id, node, callback ]);
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} else {
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this.callbacks[id] = callback;
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this.observer.observe(node);
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}
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}
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unobserve (id, node) {
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if (this.observer) {
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delete this.callbacks[id];
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this.observer.unobserve(node);
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}
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}
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disconnect () {
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if (this.observer) {
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this.callbacks = {};
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this.observer.disconnect();
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this.observer = null;
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}
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}
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}
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export default IntersectionObserverWrapper;
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