# Knowledge check: Getting started with hooks - Advanced React
1. **Imagine you have to log into the console a state variable, whenever the variable gets updated. What's the best place to perform such operation in a React component?**
* Before the return statement of the component
* the useEffect hook
2. **The** `useEffect` **hook accepts...**
* two callback functions
* a callback function and an array
* a callback function and an object
3. **What is a pure React component?**
* A component that doesn't have any side effects
* A component that has at least one side effect
4. **What is the name of the second argument of the** `useEffect()` **call?**
* the dependency array
* the callback function
* the destructured object
* the dependencies object
5. **This code is incomplete:**
```javascript
React.useEffect(()=> {
console.log('The value of the toggle variable is',toggle)
}, [])
```
**You need to update the dependecies array so that the** `useEffect` **hook is invoked whenever the toggle variable updates. Choose the correct solution from the choices below.**
* The dependencies array should receive the toggle variable as its single member.
* The dependencies array should be removed.
* The dependencies array should be updated to: \[{toggle}\].
* The dependencies array should be replaced with: {toggle}.
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