Created
January 18, 2021 14:29
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memoizeSelector
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| const memoizeSelector = (getDeps, selector) => { | |
| const lastDeps = [] | |
| let lastResult | |
| return (store) => { | |
| let updated = false | |
| const deps = getDeps.map((getDep, i) => { | |
| const dep = getDep(store) | |
| if (dep !== lastDeps[i]) { | |
| lastDeps[i] = dep | |
| updated = true | |
| } | |
| return dep | |
| }) | |
| if (updated) { | |
| lastResult = selector(store, ...deps) | |
| } | |
| return lastResult | |
| } | |
| } | |
| const selector = memoizeSelector([ | |
| (store) => store.items | |
| ], (store, items) => { | |
| return items.map((it) => it.id).join()+store.other | |
| }) | |
| const store = { | |
| items: [ | |
| { id: 1 }, | |
| { id: 2 }, | |
| { id: 3 }, | |
| ], | |
| other: 'this is the other prop' | |
| } | |
| console.log(selector(store)) | |
| store.items[0].id = 0 | |
| console.log(selector(store)) | |
| store.items = [...store.items, { id: 4 }] | |
| console.log(selector(store)) | |
| store.other = 'foo bar' | |
| console.log(selector(store)) | |
| store.items = [...store.items] | |
| console.log(selector(store)) |
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