---title: Lazynav: 3.03keywords: lazy,initialize,init,loading---
When defining primitive atoms, their initial value has to be bound at definition time.If creating that initial value is computationally expensive, or the value is not accessible during definition,it would be best to postpone the atom's initialization until its [first use in the store](#using-multiple-stores).
```jsxconst imageDataAtom = atom(initializeExpensiveImage()) // 1) has to be computed here
function Home() { ...}
function ImageEditor() { // 2) used only in this route const [imageData, setImageData] = useAtom(imageDataAtom); ...}
function App() { return ( <Router> <Route path="/" component={Home} /> <Route path="/edit" component={ImageEditor} /> </Router> )}```
## atomWithLazy
Ref: https://github.com/pmndrs/jotai/pull/2465
We can use `atomWithLazy` to create a primitive atom whose initial value will be computed at [first use in the store](#using-multiple-stores).After initialization, it will behave like a regular primitive atom (can be written to).
### Usage
```jsximport { atomWithLazy } from 'jotai/utils'
// passing the initialization functionconst imageDataAtom = atomWithLazy(initializeExpensiveImage)
function Home() { ...}
function ImageEditor() { // only gets initialized if user goes to `/edit`. const [imageData, setImageData] = useAtom(imageDataAtom); ...}
function App() { return ( <Router> <Route path="/" component={Home} /> <Route path="/edit" component={ImageEditor} /> </Router> )}```
### Using multiple stores
Since each store is its separate universe, the initial value will be recreated exactly once per store (unless using something like `jotai-scope`, which fractures a store into smaller universes).
```tstype RGB = [number, number, number];
function randomRGB(): RGB { ...}
const lift = (value: number) => ([r, g, b]: RGB) => { return [r + value, g + value, b + value]}
const colorAtom = lazyAtom(randomRGB)
let store = createStore()
console.log(store.get(colorAtom)) // [0, 36, 128]store.set(colorAtom, lift(8))console.log(store.get(colorAtom)) // [8, 44, 136]
// recreating store, sometimes done when logging out or resetting the app in some waystore = createStore()
console.log(store.get(colorAtom)) // [255, 12, 46] -- a new random color```