062 - Jotai Core ❌

atom

• atom function to create an atom config object
  • need an initial value
  • immutable
  • doesn’t hold a value
  • values exists in a store
• call it atom when the context is clear
• can create derived atoms
  • read-only
  • write-only
  • read-write

const readOnlyAtom = atom((get) => get(priceAtom) * 2)
 
const writeOnlyAtom = atom(
  null, // it's a convention to pass `null` for the first argument
  (get, set, update) => {
    // `update` is any single value we receive for updating this atom
    set(priceAtom, get(priceAtom) - update.discount)
    // or we can pass a function as the second parameter
    // the function will be invoked,
    //  receiving the atom's current value as its first parameter
    set(priceAtom, (price) => price - update.discount)
  },
)
 
const readWriteAtom = atom(
  (get) => get(priceAtom) * 2,
  (get, set, newPrice) => {
    set(priceAtom, newPrice / 2)
    // you can set as many atoms as you want at the same time
  },
)

• get in the read function is to read the atom value. It’s reactive and read dependencies are tracked
• get in the write function is also to read atom value, but it’s not tracked

useAtom

Store

Provider