52 lines
1.2 KiB
JavaScript
52 lines
1.2 KiB
JavaScript
import useForceUpdate from './useForceUpdate';
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import useStableMemo from './useStableMemo';
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export class ObservableMap extends Map {
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constructor(listener, init) {
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super(init);
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this.listener = listener;
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}
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set(key, value) {
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super.set(key, value);
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// When initializing the Map, the base Map calls this.set() before the
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// listener is assigned so it will be undefined
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if (this.listener) this.listener(this);
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return this;
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}
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delete(key) {
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let result = super.delete(key);
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this.listener(this);
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return result;
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}
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clear() {
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super.clear();
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this.listener(this);
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}
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}
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/**
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* Create and return a [Map](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) that triggers rerenders when it's updated.
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*
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* ```tsx
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* const customerAges = useMap<number>([
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* ['john', 24],
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* ['betsy', 25]
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* ]);
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*
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* return (
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* <>
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* {Array.from(ids, ([name, age]) => (
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* <div>
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* {name}: {age}. <button onClick={() => ids.delete(name)}>X</button>
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* </div>
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* )}
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* </>
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* )
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* ```
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*
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* @param init initial Map entries
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*/
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function useMap(init) {
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const forceUpdate = useForceUpdate();
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return useStableMemo(() => new ObservableMap(forceUpdate, init), []);
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}
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export default useMap; |