## Boolean

A variable value can be a Boolean, which is something that is either true or false. Example of checking if a variable called raining is false:
```if (raining == false) {
console.log(`leave the umbrella`)
}
```
The name Boolean comes from the English mathematician George Boole, who did work in the field of logic.

### Exercise 1 of 6

Write a condition to check if rich is false.

HTML

```<button id="richMessageButton">Show message</button>
<p id="richMessageParagraph"></p>
```

JavaScript

```let richMessageButton = document.getElementById(`richMessageButton`)
let richMessageParagraph = document.getElementById(`richMessageParagraph`)

let rich = false

function showRichMessage() {
if (// your code will appear here) {
richMessageParagraph.innerHTML = `Get a job`
}
}
```

### Exercise 2 of 6

Write a condition to check if famous is true.

HTML

```<button id="famousMessageButton">Show message</button>
<p id="famousMessageParagraph"></p>
```

JavaScript

```let famousMessageButton = document.getElementById(`famousMessageButton`)
let famousMessageParagraph = document.getElementById(`famousMessageParagraph`)

let famous = true

function showFamousMessage() {
if (// your code will appear here) {
famousMessageParagraph.innerHTML = `Everybody knows you`
}
}
```

### Exercise 3 of 6

Write a condition to toggle the light.

HTML

```<button id="lightButton">Flip switch</button>
<p id="lightParagraph">Dark</p>
```

JavaScript

```let lightButton = document.getElementById(`lightButton`)
let lightParagraph = document.getElementById(`lightParagraph`)

let lightOn = false

function flipSwitch() {
if (// your code will appear here) {
lightParagraph.innerHTML = `Light`
lightOn = true
}
else {
lightParagraph.innerHTML = `Dark`
lightOn = false
}
}
```

Dark

### Exercise 4 of 6

Write a condition to toggle the player turn.

HTML

```<button id="turnButton">Take turn</button>
<p id="turnParagraph">Player 1's turn</p>
```

JavaScript

```let turnButton = document.getElementById(`turnButton`)
let turnParagraph = document.getElementById(`turnParagraph`)

let player1Turn = true

function takeTurn() {
if (// your code will appear here) {
turnParagraph.innerHTML = `Player 2's turn`
player1Turn = false
}
else {
turnParagraph.innerHTML = `Player 1's turn`
player1Turn = true
}
}
```

Player 1's turn

### Exercise 5 of 6

Set catVisible so that clicking the cat toggles its opacity.

HTML

```<img src="/img/cat.png" id="cat">
```

JavaScript

```let cat = document.getElementById(`cat`)

let catVisible = true

function toggleOpacity() {
if (catVisible == true) {
this.style.opacity = `0%`
// your code will appear here
}
else {
this.style.opacity = `100%`
catVisible = true
}
}
```

### Exercise 6 of 6

Set dogRotated so that clicking the dog toggles its rotation.

HTML

```<img src="/img/dog.png" id="dog">
```

JavaScript

```let dog = document.getElementById(`dog`)

let dogRotated = false

function toggleRotation() {
if (dogRotated == false) {
this.style.transform = `rotate(180deg)`
// your code will appear here
}
else {
this.style.transform = `rotate(0deg)`
dogRotated = false
}
}
```