---
id: 62a8e4dc6a60f85bf256a0cb
title: Step 124
challengeType: 0
dashedName: step-124
---
# --description--
The `Math` object in JavaScript contains static properties and methods for mathematical constants and functions. One of those is `Math.random()`, which generates a random number from `0` (inclusive) to `1` (exclusive). Another is `Math.floor()`, which rounds a given number down to the nearest integer.
Using these, you can generate a random number within a range. For example, this generates a random number between `1` and `5`: `Math.floor(Math.random() * 5) + 1;`.
Following this pattern, use the addition operator (`+`) to add a random number between `1` and the value of `xp` to your `monsterHealth -= weapons[currentWeaponIndex].power`.
# --hints--
You should use the same `monsterHealth` line you already wrote.
```js
assert.lengthOf(attack.toString().match(/monsterHealth/g), 1);
```
You should add to the `weapons[currentWeaponIndex].power` value.
```js
assert.match(attack.toString(), /monsterHealth\s*-=\s*weapons\s*\[\s*currentWeaponIndex\s*\]\s*\.power\s*\+/);
```
You should use `Math.floor()`.
```js
assert.match(attack.toString(), /Math\.floor/);
```
You should use `Math.random()`.
```js
assert.match(attack.toString(), /Math\.random/);
```
You should multiply `Math.random()` by the value of `xp`.
```js
assert.match(attack.toString(), /Math\.random\(\s*\)\s*\*\s*xp/);
```
You should use `Math.floor()` to round the result of `Math.random() * xp` down.
```js
assert.match(attack.toString(), /Math\.floor\(\s*Math\.random\(\s*\)\s*\*\s*xp\s*.*\)/);
```
You should add `1` to the result of `Math.floor()`.
```js
assert.match(attack.toString(), /Math\.floor\(\s*Math\.random\(\s*\)\s*\*\s*xp(?:\s*\+\s*1)?\s*\)(?:\s*\+ 1)?/);
```
You should add the result of `Math.floor(Math.random() * xp) + 1` to the result of `weapons[currentWeapon].power`.
```js
assert.match(attack.toString(), /monsterHealth\s*-=\s*weapons\s*\[\s*currentWeaponIndex\s*\]\s*\.power\s*\+\s*Math\.floor\(\s*Math\.random\(\s*\)\s*\*\s*xp(?:\s*\+\s*1)?\s*\)(?:\s*\+ 1)?/);
```
# --seed--
## --seed-contents--
```html
RPG - Dragon Repeller
XP: 0Health: 100Gold: 50
Monster Name: Health:
Welcome to Dragon Repeller. You must defeat the dragon that is preventing people from leaving the town. You are in the town square. Where do you want to go? Use the buttons above.
```
```css
body {
background-color: #0a0a23;
}
#text {
background-color: #0a0a23;
color: #ffffff;
padding: 10px;
}
#game {
max-width: 500px;
max-height: 400px;
background-color: #ffffff;
color: #ffffff;
margin: 30px auto 0px;
padding: 10px;
}
#controls,
#stats {
border: 1px solid #0a0a23;
padding: 5px;
color: #0a0a23;
}
#monsterStats {
display: none;
border: 1px solid #0a0a23;
padding: 5px;
color: #ffffff;
background-color: #c70d0d;
}
.stat {
padding-right: 10px;
}
button {
cursor: pointer;
color: #0a0a23;
background-color: #feac32;
background-image: linear-gradient(#fecc4c, #ffac33);
border: 3px solid #feac32;
}
```
```js
let xp = 0;
let health = 100;
let gold = 50;
let currentWeaponIndex = 0;
let fighting;
let monsterHealth;
let inventory = ["stick"];
const button1 = document.querySelector('#button1');
const button2 = document.querySelector("#button2");
const button3 = document.querySelector("#button3");
const text = document.querySelector("#text");
const xpText = document.querySelector("#xpText");
const healthText = document.querySelector("#healthText");
const goldText = document.querySelector("#goldText");
const monsterStats = document.querySelector("#monsterStats");
const monsterName = document.querySelector("#monsterName");
const monsterHealthText = document.querySelector("#monsterHealth");
const weapons = [
{ name: 'stick', power: 5 },
{ name: 'dagger', power: 30 },
{ name: 'claw hammer', power: 50 },
{ name: 'sword', power: 100 }
];
const monsters = [
{
name: "slime",
level: 2,
health: 15
},
{
name: "fanged beast",
level: 8,
health: 60
},
{
name: "dragon",
level: 20,
health: 300
}
]
const locations = [
{
name: "town square",
"button text": ["Go to store", "Go to cave", "Fight dragon"],
"button functions": [goStore, goCave, fightDragon],
text: "You are in the town square. You see a sign that says \"Store\"."
},
{
name: "store",
"button text": ["Buy 10 health (10 gold)", "Buy weapon (30 gold)", "Go to town square"],
"button functions": [buyHealth, buyWeapon, goTown],
text: "You enter the store."
},
{
name: "cave",
"button text": ["Fight slime", "Fight fanged beast", "Go to town square"],
"button functions": [fightSlime, fightBeast, goTown],
text: "You enter the cave. You see some monsters."
},
{
name: "fight",
"button text": ["Attack", "Dodge", "Run"],
"button functions": [attack, dodge, goTown],
text: "You are fighting a monster."
}
];
// initialize buttons
button1.onclick = goStore;
button2.onclick = goCave;
button3.onclick = fightDragon;
function update(location) {
button1.innerText = location["button text"][0];
button2.innerText = location["button text"][1];
button3.innerText = location["button text"][2];
button1.onclick = location["button functions"][0];
button2.onclick = location["button functions"][1];
button3.onclick = location["button functions"][2];
text.innerText = location.text;
}
function goTown() {
update(locations[0]);
}
function goStore() {
update(locations[1]);
}
function goCave() {
update(locations[2]);
}
function buyHealth() {
if (gold >= 10) {
gold -= 10;
health += 10;
goldText.innerText = gold;
healthText.innerText = health;
} else {
text.innerText = "You do not have enough gold to buy health.";
}
}
function buyWeapon() {
if (currentWeaponIndex < weapons.length - 1) {
if (gold >= 30) {
gold -= 30;
currentWeaponIndex++;
goldText.innerText = gold;
let newWeapon = weapons[currentWeaponIndex].name;
text.innerText = "You now have a " + newWeapon + ".";
inventory.push(newWeapon);
text.innerText += " In your inventory you have: " + inventory;
} else {
text.innerText = "You do not have enough gold to buy a weapon.";
}
} else {
text.innerText = "You already have the most powerful weapon!";
button2.innerText = "Sell weapon for 15 gold";
button2.onclick = sellWeapon;
}
}
function sellWeapon() {
if (inventory.length > 1) {
gold += 15;
goldText.innerText = gold;
let currentWeapon = inventory.shift();
text.innerText = "You sold a " + currentWeapon + ".";
text.innerText += " In your inventory you have: " + inventory;
} else {
text.innerText = "Don't sell your only weapon!";
}
}
function fightSlime() {
fighting = 0;
goFight();
}
function fightBeast() {
fighting = 1;
goFight();
}
function fightDragon() {
fighting = 2;
goFight();
}
function goFight() {
update(locations[3]);
monsterHealth = monsters[fighting].health;
monsterStats.style.display = "block";
monsterName.innerText = monsters[fighting].name;
monsterHealthText.innerText = monsterHealth;
}
function attack() {
text.innerText = "The " + monsters[fighting].name + " attacks.";
text.innerText += " You attack it with your " + weapons[currentWeaponIndex].name + ".";
health -= monsters[fighting].level;
--fcc-editable-region--
monsterHealth -= weapons[currentWeaponIndex].power;
--fcc-editable-region--
}
function dodge() {
}
```