# @emotion/weak-memoize
> A memoization function that uses a WeakMap
## Install
```bash
yarn add @emotion/weak-memoize
```
## Usage
Because @emotion/weak-memoize uses a WeakMap the argument must be a non primitive type, e.g. objects, functions, arrays and etc. The function passed to `weakMemoize` must also only accept a single argument.
```jsx
import weakMemoize from '@emotion/weak-memoize'
let doThing = weakMemoize(({ someProperty }) => {
return { newName: someProperty }
})
let obj = { someProperty: true }
let firstResult = doThing(obj)
let secondResult = doThing(obj)
firstResult === secondResult // true
let newObj = { someProperty: true }
let thirdResult = doThing(newObj)
thirdResult === firstResult // false
```