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Lesson 4

Lesson 4 of 16

Operators

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Code Example

let sum = 5 + 3;
console.log(sum); // the answer should be 8

let result = 10 - 4;
console.log(result); // the answer should be 6

let product = 6 * 2;
console.log(product); // 12

let quotient = 20 / 5;
console.log(quotient); // 4

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A list is like a backpack where you can keep many different items together.
If you want to add something new to the end of your list, you use the append() helper.
Just tell Python which list you are using, then add the new item inside the parentheses.
For example, fruits.append("cherry") puts a cherry at the very end of your fruit list.

Code Example

let remainder = 10 % 3;
console.log(remainder); // the answer should be 1

// Sharing 7 slices of pizza with 2 people
let pizzaLeftover = 7 % 2;
console.log(pizzaLeftover); // the answer should be 1

// Putting 12 toys into 4 equal boxes
let toyLeftover = 12 % 4;
console.log(toyLeftover); // 0

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Sometimes you have two different lists and you want to join them together into one big list.
Python has a helper called extend() that lets you pour one list into another.
It doesn't just add one item; it adds every single item from the second list to the end of the first one.
It's like taking two boxes of toys and dumping the smaller box into the bigger one to keep them all together.

Code Example

let x = 7;
console.log(x); // the answer should be 7

// Keeping track of a player's lives
let lives = 3;
console.log(lives); // the answer should be 3

// Counting how many gold coins you found
let coins = 50;
console.log(coins); // the answer should be 50

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We can use a name like lives to store the number 3 so the computer remembers it.
When we use console.log, we are telling the computer to "read out loud" what is in the box.
You can change the number inside the box whenever you want, like when you find more coins!

Code Example

console.log(5 == 5); // true

// Example 1: Comparing a number and a string
console.log(10 == 10); // true

console.log(5 == "5"); // true

// Example 1: Comparing a number and a string
console.log(10 == "10"); // true

// Example 2: Comparing the number zero and an empty-looking string
console.log(0 == ""); // true

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The double equals == is like a "close enough" check that looks at the meaning of the data.
It sees that the number 10 and the word "10" are twins, even though one is wearing "quote" clothes.
Sometimes it gets silly, like thinking 0 and an empty message "" are the same thing!
While this "friendly" check is helpful, most coders use a triple equals === for a much stricter "exact match" test.

Code Example

const b = 5;
console.log(5 === b); // true

const c = 10;
console.log(10 === c); // true

console.log(5 === "5"); // false

// Example 1: Strict check between a number and a string
console.log(10 === "10"); // false

// Example 2: Strict check between a number and a boolean
console.log(1 === true); // false

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The triple equals === is a strict judge that requires things to be exactly the same.
It says false for 10 === "10" because a plain number is not the same as a word.
Even if the values look similar, this check makes sure the "type" of the box matches perfectly too.
Most professional coders prefer this strict way because it prevents the computer from making silly guesses.

Code Example

let count = 5;
count++;
console.log(count); // 6

// Giving a player a point in a video game
let score = 10;
score++;
console.log(score); // 11

// Counting how many levels you finished
let level = 1;
level++;
console.log(level); // 2

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The ++ symbol is a shortcut that tells the computer to "add one" to your number.
It is like a scoreboard that automatically clicks up by one every time you do something cool.
You can use it to keep track of how many items you have collected in a treasure hunt.
Instead of writing a long math problem, you just put ++ after the name to grow the number.

Code Example

let count = 5;
count--;
console.log(count); // 4 

// Losing a life in a game
let hearts = 3;
hearts--;
console.log(hearts); // 2

// Counting down the remaining cookies
let cookiesInJar = 10;
cookiesInJar--;
console.log(cookiesInJar); // 9

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The -- symbol is a quick shortcut that tells the computer to "subtract one" from your number.
It works exactly like a countdown, lowering the value by one every time the computer reads it.
You can use it to track how many tries a player has left before the game is over.
It is much faster than writing a long math equation when you just need to take away a single point.

Code Example

const guests = 5;
const meals = 4;
console.log(persons > seats);

// Checking if you have enough gold to buy a sword
const swordPrice = 10;
const myGold = 8;
console.log(myGold > swordPrice); 

// Checking if a car can fit under a bridge
const bridgeHeight = 12;
const carHeight = 9;
console.log(carHeight < bridgeHeight);

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The < and > symbols are like "Comparison Crocodiles" that check which number is bigger.
The computer gives you a true or false answer based on whether the rule you wrote is correct.
This is how games decide if you have enough points to level up or enough room to fit an item in your bag.
It helps the computer make simple decisions by comparing two different "boxes" of information.

Code Example

const guests = 5;
const meals = 4;
console.log(guests > meals);

// Checking if you have enough fuel for your rocket
const fuelNeeded = 100;
const fuelLevel = 150;
console.log(fuelLevel > fuelNeeded); 

// Checking if your backpack is too heavy
const maxWeight = 20;
const currentWeight = 25;
console.log(currentWeight > maxWeight);

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The > symbol is like a hungry crocodile that always wants to open its mouth toward the bigger number.
If the number on the left is bigger than the one on the right, the computer will give you a true answer.
This is a great tool for checking if you have "too much" of something, like a backpack that is getting too heavy.
It helps your program make smart choices, like deciding if a rocket has enough fuel to blast off into space!

Code Example

const leashes = 7;
const puppies = 3;
console.log(leashes >= puppies); 

// Checking if you have enough fuel for your rocket
const fuelNeeded = 100;
const fuelLevel = 150;
console.log(fuelLevel >= fuelNeeded); 

// Checking if your backpack is too heavy
const maxWeight = 20;
const currentWeight = 25;
console.log(currentWeight >= maxWeight);

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The >= symbol checks if the first number is bigger than OR exactly the same as the second one.
It is like a "Fair Share" rule that says true as long as you have enough for everyone, even if it's a perfect fit.
You can use this to see if a player has enough points to buy a new skin or unlock a secret level.
It combines the "Bigger Than" sign and the "Equals" sign into one powerful tool for making decisions.

Code Example

const cars = 2;
const parkingSpaces = 5;
console.log(cars <= parkingSpaces); 

// Can your group fit on a bench made for 3 people?
const people = 3;
const benchSeats = 3;
console.log(people <= benchSeats); // true (A perfect fit!)

// Is your suitcase light enough for the airplane?
const maxWeight = 50;
const myBagWeight = 42;
console.log(myBagWeight <= maxWeight); // true (It's under the limit!)

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The <= symbol checks if a number is smaller than or exactly equal to another number.
It is like a "Safety Limit" that says true as long as you don't go over the maximum allowed amount.
You can use this to see if a player is still young enough to play in a "Junior" game league.
It combines the "Less Than" sign and the "Equals" sign to make sure you stay within the right boundaries.

Code Example

const cars = 2;
cars += 1;
console.log(cars);
cars += 3;
console.log(cars) 

// Example 1: Gaining experience points (XP) in a game
let xp = 100;
xp += 50;
console.log(xp); // 150

// Example 2: Adding items to a shopping cart
let cartTotal = 2;
cartTotal += 1;
console.log(cartTotal); // 3
cartTotal += 5;
console.log(cartTotal); // 8

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The += symbol is a power-up that adds a new number to the current total and saves it.
It is like a piggy bank—you don't throw away what's inside; you just add more coins to the pile.
You can use it to increase a player's speed, health, or score as they move through your game.
It is a much cleaner way to write cars = cars + 1 by combining the math and the saving into one step.

Code Example

const cars = 25;
cars -= 1;
console.log(cars);
cars -= 3;
console.log(cars);

// Example 1: Spending gold coins in a shop
let gold = 100;
gold -= 20;
console.log(gold); // 80

// Example 2: Fuel leaking from a gas tank
let fuel = 50;
fuel -= 5;
console.log(fuel); // 45
fuel -= 10;
console.log(fuel); // 35

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The -= symbol is a shortcut that subtracts a number from the total and saves the new result.
It is like a "Spending" button—it looks at how much you have and immediately takes some away.
You can use it to lower a character's health when they get hit or to reduce the number of arrows in a quiver.
Instead of writing out a long math sentence, it keeps your code tidy by doing the subtraction and saving in one go.

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Operators

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Lesson 4 of 16

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let sum = 5 + 3; console.log(sum); // the answer should be 8 let result = 10 - 4; console.log(result); // the answer should be 6 let product = 6 * 2; console.log(product); // 12 let quotient = 20 / 5; console.log(quotient); // 4

let remainder = 10 % 3; console.log(remainder); // the answer should be 1 // Sharing 7 slices of pizza with 2 people let pizzaLeftover = 7 % 2; console.log(pizzaLeftover); // the answer should be 1 // Putting 12 toys into 4 equal boxes let toyLeftover = 12 % 4; console.log(toyLeftover); // 0

let x = 7; console.log(x); // the answer should be 7 // Keeping track of a player's lives let lives = 3; console.log(lives); // the answer should be 3 // Counting how many gold coins you found let coins = 50; console.log(coins); // the answer should be 50

console.log(5 == 5); // true // Example 1: Comparing a number and a string console.log(10 == 10); // true console.log(5 == "5"); // true // Example 1: Comparing a number and a string console.log(10 == "10"); // true // Example 2: Comparing the number zero and an empty-looking string console.log(0 == ""); // true

const b = 5; console.log(5 === b); // true const c = 10; console.log(10 === c); // true console.log(5 === "5"); // false // Example 1: Strict check between a number and a string console.log(10 === "10"); // false // Example 2: Strict check between a number and a boolean console.log(1 === true); // false

let count = 5; count++; console.log(count); // 6 // Giving a player a point in a video game let score = 10; score++; console.log(score); // 11 // Counting how many levels you finished let level = 1; level++; console.log(level); // 2

let count = 5; count--; console.log(count); // 4 // Losing a life in a game let hearts = 3; hearts--; console.log(hearts); // 2 // Counting down the remaining cookies let cookiesInJar = 10; cookiesInJar--; console.log(cookiesInJar); // 9

const guests = 5; const meals = 4; console.log(persons > seats); // Checking if you have enough gold to buy a sword const swordPrice = 10; const myGold = 8; console.log(myGold > swordPrice); // Checking if a car can fit under a bridge const bridgeHeight = 12; const carHeight = 9; console.log(carHeight < bridgeHeight);

const guests = 5; const meals = 4; console.log(guests > meals); // Checking if you have enough fuel for your rocket const fuelNeeded = 100; const fuelLevel = 150; console.log(fuelLevel > fuelNeeded); // Checking if your backpack is too heavy const maxWeight = 20; const currentWeight = 25; console.log(currentWeight > maxWeight);

const leashes = 7; const puppies = 3; console.log(leashes >= puppies); // Checking if you have enough fuel for your rocket const fuelNeeded = 100; const fuelLevel = 150; console.log(fuelLevel >= fuelNeeded); // Checking if your backpack is too heavy const maxWeight = 20; const currentWeight = 25; console.log(currentWeight >= maxWeight);

const cars = 2; const parkingSpaces = 5; console.log(cars <= parkingSpaces); // Can your group fit on a bench made for 3 people? const people = 3; const benchSeats = 3; console.log(people <= benchSeats); // true (A perfect fit!) // Is your suitcase light enough for the airplane? const maxWeight = 50; const myBagWeight = 42; console.log(myBagWeight <= maxWeight); // true (It's under the limit!)

const cars = 2; cars += 1; console.log(cars); cars += 3; console.log(cars) // Example 1: Gaining experience points (XP) in a game let xp = 100; xp += 50; console.log(xp); // 150 // Example 2: Adding items to a shopping cart let cartTotal = 2; cartTotal += 1; console.log(cartTotal); // 3 cartTotal += 5; console.log(cartTotal); // 8

const cars = 25; cars -= 1; console.log(cars); cars -= 3; console.log(cars); // Example 1: Spending gold coins in a shop let gold = 100; gold -= 20; console.log(gold); // 80 // Example 2: Fuel leaking from a gas tank let fuel = 50; fuel -= 5; console.log(fuel); // 45 fuel -= 10; console.log(fuel); // 35