memoizeSelector

memoizeSelector.js

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))