// ============================================
// JAVASCRIPT ASSIGNMENTS
// ============================================
// ============================================
// VARIABLES
// ============================================
// 1. var, let, const
var bunny = "Lucy";
let dog = "Tom";
const cat = "Molly";
console.log(bunny);
console.log(dog);
console.log(cat);
// 2. Valid and invalid variable names
// 1bunny - invalid
// Correct version:
let bunny1;
// _bunny - valid
let _bunny = "Lucy";
// $bunny - valid
let $bunny = "Lucy";
// -bunny - invalid
// Correct version:
let bunnyName;
// @bunny - invalid
// Correct version:
let bunnyAt;
// bunnyName - valid
let validBunnyName = "Lucy";
console.log(bunny1, _bunny, $bunny, bunnyName, bunnyAt, validBunnyName);
// 3. Predicting var and let
console.log(pet);
var pet = "lucy";
// Output: undefined
// var is hoisted, so the variable declaration is known before execution,
// but its value is assigned only when that line is reached.
// console.log(animal);
// let animal = "tom";
// This causes a ReferenceError because let variables cannot be accessed
// before their declaration.
/*
4. Local and global variables
*/
let globalAnimal = "Bunny";
function animalName() {
let localAnimal = "Lucy";
console.log("Local variable:", localAnimal);
console.log("Global variable:", globalAnimal);
}
animalName();
// ============================================
// DATA TYPES
// ============================================
// 5. Object
const bunnyObject = {
name: "Lucy",
age: 3,
isHappy: true
};
console.log(bunnyObject.name);
console.log(bunnyObject.age);
console.log(bunnyObject.isHappy);
// 6. typeof
console.log(3.14, typeof 3.14);
console.log("Lucy", typeof "Lucy");
console.log(true, typeof true);
console.log(null, typeof null);
console.log(undefined, typeof undefined);
console.log(Symbol("Lucy"), typeof Symbol("Lucy"));
console.log({ name: "Lucy" }, typeof { name: "Lucy" });
console.log(["Lucy", "Tom"], typeof ["Lucy", "Tom"]);
// 7. Mixed data types
const mixedDataTypes = [
true,
25,
"Lucy",
null,
undefined,
{ name: "Tom" }
];
console.log(mixedDataTypes);
console.log("Length:", mixedDataTypes.length);
// ============================================
// FUNCTIONS
// ============================================
// 8. Function with no parameters
function sumBunnies() {
const blackBunnies = 10;
const whiteBunnies = 20;
return blackBunnies + whiteBunnies;
}
console.log(sumBunnies());
// 9. Function with parameters
function sumBunniesWithParameters(blackBunnies, whiteBunnies) {
return blackBunnies + whiteBunnies;
}
console.log(sumBunniesWithParameters(10, 20));
console.log(sumBunniesWithParameters(7, 3));
// 10a. Anonymous function
const anonymousSum = function (blackBunnies, whiteBunnies) {
return blackBunnies + whiteBunnies;
};
console.log(anonymousSum(10, 20));
// 10b. Arrow function
const arrowSum = (blackBunnies, whiteBunnies) => {
return blackBunnies + whiteBunnies;
};
console.log(arrowSum(10, 20));
// 11. IIFE
(function () {
const blackBunnies = 10;
const whiteBunnies = 20;
console.log("IIFE total:", blackBunnies + whiteBunnies);
})();
// ============================================
// ARRAYS
// ============================================
// 12. Array manipulation
const bunnyNames = [
"Lucy",
"Tom",
"Molly",
"Bella",
"Max",
"Charlie"
];
bunnyNames.push("Mario");
bunnyNames.unshift("Luigi");
// Remove Lucy
const lucyIndex = bunnyNames.indexOf("Lucy");
if (lucyIndex !== -1) {
bunnyNames.splice(lucyIndex, 1);
}
console.log(bunnyNames);
// 13. Array access
const bunnies = ["Lucy", "Tom", "Molly", "Bella"];
console.log("First item:", bunnies[0]);
console.log(
"Last item:",
bunnies[bunnies.length - 1]
);
console.log(
"Index of Tom:",
bunnies.indexOf("Tom")
);
const bunniesCopy = [...bunnies];
console.log("Copy:", bunniesCopy);
// 14. Loop through bunnies
for (let i = 0; i < bunnies.length; i++) {
console.log(
Bunny ${bunnies[i]} is scheduled for a checkup today.
);
}
// 15. Nested arrays
const nestedArrays = [
["Lucy", "Tom"],
["Molly", "Bella"]
];
console.log(nestedArrays[0][0]); // Lucy
console.log(nestedArrays[1][1]); // Bella
for (let i = 0; i < nestedArrays.length; i++) {
for (let j = 0; j < nestedArrays[i].length; j++) {
console.log(nestedArrays[i][j]);
}
}
// ============================================
// JSON
// ============================================
// 16. JavaScript object -> JSON
const bunnyForJSON = {
name: "Lucy",
age: 3,
isHappy: true
};
const bunnyJSON = JSON.stringify(bunnyForJSON);
console.log(bunnyJSON);
// 17. JSON -> JavaScript object
let bunnyJSON2 = '{"name":"Lucy","age":3,"isHappy":true}';
const bunnyFromJSON = JSON.parse(bunnyJSON2);
console.log(bunnyFromJSON.name);
console.log(bunnyFromJSON.age);
// ============================================
// COMPARISON OPERATORS
// ============================================
// 18. ==, ===, !=, !==
let bunny_age = 3;
let dog_age = "3";
console.log(bunny_age == dog_age); // true
console.log(bunny_age === dog_age); // false
console.log(bunny_age != dog_age); // false
console.log(bunny_age !== dog_age); // true
// == compares values after type conversion,
// while === compares both value and type.
// 19. Compare array lengths
const bunniesForComparison = [
"Lucy",
"Tom",
"Molly"
];
const dogs = [
"Max",
"Buddy",
"Charlie",
"Rocky"
];
if (bunniesForComparison.length <= dogs.length) {
console.log("There are more dogs than bunnies");
} else {
console.log("There are more bunnies than dogs");
}
// ============================================
// CONDITIONAL STATEMENTS
// ============================================
// 20a. if / else if / else
const health = "healthy";
if (health === "healthy") {
console.log("Bunny is healthy");
} else if (health === "sick") {
console.log("Bunny is sick");
} else {
console.log("Unknown health status");
}
// 20b. switch statement
switch (health) {
case "healthy":
console.log("Bunny is healthy");
break;
case "sick":
console.log("Bunny is sick");
break;
default:
console.log("Unknown health status");
}
// 20c. Ternary operator
const healthMessage =
health === "healthy" ? "Bunny is healthy" : "Bunny is not healthy";
console.log(healthMessage);
// 21. Even or odd using ternary
function evenOrOdd(number) {
return number % 2 === 0 ? "even" : "odd";
}
console.log(evenOrOdd(4));
console.log(evenOrOdd(7));
console.log(evenOrOdd(0));
// ============================================
// LOOPS
// ============================================
// 22a. for loop: 0 through 9
for (let i = 0; i <= 9; i++) {
console.log("Number", i);
}
// 22b. while loop: 0 through 9
let number = 0;
while (number <= 9) {
console.log("Number", number);
number++;
}
// 23a. while loop countdown 9 to 1
let countdown = 9;
while (countdown >= 1) {
console.log(countdown);
countdown--;
}
// 23b. for loop countdown 9 to 1
for (let i = 9; i >= 1; i--) {
console.log(i);
}
// ============================================
// EXCEPTION HANDLING AND OPERATORS
// ============================================
// 24. Error handling
function sumBunniesWithValidation(blackBunnies, whiteBunnies) {
if (
typeof blackBunnies !== "number" ||
typeof whiteBunnies !== "number"
) {
throw new Error("Both arguments must be numbers");
}
return blackBunnies + whiteBunnies;
}
try {
console.log(sumBunniesWithValidation(10, "twenty"));
} catch (error) {
console.log(error.message);
}
// 25. Operators
let blackBunnies = 10;
let whiteBunnies = 5;
const totalBunnies = blackBunnies + whiteBunnies;
console.log(
"Are black and white bunnies equal?",
blackBunnies === whiteBunnies
);
console.log("Total bunnies:", totalBunnies);
console.log(
"Are there more than 12 bunnies?",
totalBunnies > 12
);
const answer = totalBunnies > 12 ? "Yes" : "No";
console.log(answer);
// ============================================
// BRAIN TEASERS
// ============================================
// Brain Teaser 1 — The quiet loop
let carrots = 3;
while (carrots) {
console.log("munch");
carrots--;
}
/*
Output:
munch
munch
munch
The loop stops when carrots becomes 0 because 0 is falsy.
If carrots-- were deleted, carrots would remain 3 forever,
so the loop would become an infinite loop.
*/
// Brain Teaser 2 — For loop
const bunnyList = [
"Lucy",
"Tom",
"Molly",
"Bella",
"Mario",
"Luigi"
];
for (let i = 0; i < bunnyList.length; i++) {
if (bunnyList[i].length > 4) {
console.log(bunnyList[i]);
}
}
// Brain Teaser 2 — While loop
let i = 0;
while (i < bunnyList.length) {
if (bunnyList[i].length > 4) {
console.log(bunnyList[i]);
}
i++;
}
// Brain Teaser 3 — Nested checkup
const nestedBunnies = [
["Lucy", "Tom"],
["Molly", "Bella"],
["Mario", "Luigi"]
];
let count = 1;
for (let i = 0; i < nestedBunnies.length; i++) {
for (let j = 0; j < nestedBunnies[i].length; j++) {
console.log(${count}. ${nestedBunnies[i][j]});
count++;
}
}
// Brain Teaser 4 — Loop + condition + function
function countHappyBunnies(bunnies) {
let happyCount = 0;
for (let i = 0; i < bunnies.length; i++) {
if (bunnies[i].isHappy === true) {
happyCount++;
}
}
return happyCount;
}
const happyBunnies = [
{ name: "Lucy", isHappy: true },
{ name: "Tom", isHappy: false },
{ name: "Molly", isHappy: true }
];
const happyCount = countHappyBunnies(happyBunnies);
const happinessMessage =
happyCount >= happyBunnies.length / 2
? "Most bunnies are happy"
: "Most bunnies are not happy";
console.log(happinessMessage);
// Brain Teaser 5 — Snippet A
for (let i = 0; i < 5; i++) {
console.log(i);
}
// Brain Teaser 5 — Snippet B (fixed)
let j = 0;
while (j < 5) {
console.log(j);
j++;
}
/*
When to pick for vs while:
Use a for loop when you know the number/range of repetitions,
and use a while loop when repetition mainly depends on a condition.
*/// ============================================
// JAVASCRIPT ASSIGNMENTS
// ============================================
// ============================================
// VARIABLES
// ============================================
// 1. var, let, const
var bunny = "Lucy";
let dog = "Tom";
const cat = "Molly";
console.log(bunny);
console.log(dog);
console.log(cat);
// 2. Valid and invalid variable names
// 1bunny - invalid
// Correct version:
let bunny1;
// _bunny - valid
let _bunny = "Lucy";
// $bunny - valid
let $bunny = "Lucy";
// -bunny - invalid
// Correct version:
let bunnyName;
// @bunny - invalid
// Correct version:
let bunnyAt;
// bunnyName - valid
let validBunnyName = "Lucy";
console.log(bunny1, _bunny, $bunny, bunnyName, bunnyAt, validBunnyName);
// 3. Predicting var and let
console.log(pet);
var pet = "lucy";
// Output: undefined
// var is hoisted, so the variable declaration is known before execution,
// but its value is assigned only when that line is reached.
// console.log(animal);
// let animal = "tom";
// This causes a ReferenceError because let variables cannot be accessed
// before their declaration.
/*
4. Local and global variables
*/
let globalAnimal = "Bunny";
function animalName() {
let localAnimal = "Lucy";
console.log("Local variable:", localAnimal);
console.log("Global variable:", globalAnimal);
}
animalName();
// ============================================
// DATA TYPES
// ============================================
// 5. Object
const bunnyObject = {
name: "Lucy",
age: 3,
isHappy: true
};
console.log(bunnyObject.name);
console.log(bunnyObject.age);
console.log(bunnyObject.isHappy);
// 6. typeof
console.log(3.14, typeof 3.14);
console.log("Lucy", typeof "Lucy");
console.log(true, typeof true);
console.log(null, typeof null);
console.log(undefined, typeof undefined);
console.log(Symbol("Lucy"), typeof Symbol("Lucy"));
console.log({ name: "Lucy" }, typeof { name: "Lucy" });
console.log(["Lucy", "Tom"], typeof ["Lucy", "Tom"]);
// 7. Mixed data types
const mixedDataTypes = [
true,
25,
"Lucy",
null,
undefined,
{ name: "Tom" }
];
console.log(mixedDataTypes);
console.log("Length:", mixedDataTypes.length);
// ============================================
// FUNCTIONS
// ============================================
// 8. Function with no parameters
function sumBunnies() {
const blackBunnies = 10;
const whiteBunnies = 20;
return blackBunnies + whiteBunnies;
}
console.log(sumBunnies());
// 9. Function with parameters
function sumBunniesWithParameters(blackBunnies, whiteBunnies) {
return blackBunnies + whiteBunnies;
}
console.log(sumBunniesWithParameters(10, 20));
console.log(sumBunniesWithParameters(7, 3));
// 10a. Anonymous function
const anonymousSum = function (blackBunnies, whiteBunnies) {
return blackBunnies + whiteBunnies;
};
console.log(anonymousSum(10, 20));
// 10b. Arrow function
const arrowSum = (blackBunnies, whiteBunnies) => {
return blackBunnies + whiteBunnies;
};
console.log(arrowSum(10, 20));
// 11. IIFE
(function () {
const blackBunnies = 10;
const whiteBunnies = 20;
console.log("IIFE total:", blackBunnies + whiteBunnies);
})();
// ============================================
// ARRAYS
// ============================================
// 12. Array manipulation
const bunnyNames = [
"Lucy",
"Tom",
"Molly",
"Bella",
"Max",
"Charlie"
];
bunnyNames.push("Mario");
bunnyNames.unshift("Luigi");
// Remove Lucy
const lucyIndex = bunnyNames.indexOf("Lucy");
if (lucyIndex !== -1) {
bunnyNames.splice(lucyIndex, 1);
}
console.log(bunnyNames);
// 13. Array access
const bunnies = ["Lucy", "Tom", "Molly", "Bella"];
console.log("First item:", bunnies[0]);
console.log(
"Last item:",
bunnies[bunnies.length - 1]
);
console.log(
"Index of Tom:",
bunnies.indexOf("Tom")
);
const bunniesCopy = [...bunnies];
console.log("Copy:", bunniesCopy);
// 14. Loop through bunnies
for (let i = 0; i < bunnies.length; i++) {
console.log(
Bunny ${bunnies[i]} is scheduled for a checkup today.
);
}
// 15. Nested arrays
const nestedArrays = [
["Lucy", "Tom"],
["Molly", "Bella"]
];
console.log(nestedArrays[0][0]); // Lucy
console.log(nestedArrays[1][1]); // Bella
for (let i = 0; i < nestedArrays.length; i++) {
for (let j = 0; j < nestedArrays[i].length; j++) {
console.log(nestedArrays[i][j]);
}
}
// ============================================
// JSON
// ============================================
// 16. JavaScript object -> JSON
const bunnyForJSON = {
name: "Lucy",
age: 3,
isHappy: true
};
const bunnyJSON = JSON.stringify(bunnyForJSON);
console.log(bunnyJSON);
// 17. JSON -> JavaScript object
let bunnyJSON2 = '{"name":"Lucy","age":3,"isHappy":true}';
const bunnyFromJSON = JSON.parse(bunnyJSON2);
console.log(bunnyFromJSON.name);
console.log(bunnyFromJSON.age);
// ============================================
// COMPARISON OPERATORS
// ============================================
// 18. ==, ===, !=, !==
let bunny_age = 3;
let dog_age = "3";
console.log(bunny_age == dog_age); // true
console.log(bunny_age === dog_age); // false
console.log(bunny_age != dog_age); // false
console.log(bunny_age !== dog_age); // true
// == compares values after type conversion,
// while === compares both value and type.
// 19. Compare array lengths
const bunniesForComparison = [
"Lucy",
"Tom",
"Molly"
];
const dogs = [
"Max",
"Buddy",
"Charlie",
"Rocky"
];
if (bunniesForComparison.length <= dogs.length) {
console.log("There are more dogs than bunnies");
} else {
console.log("There are more bunnies than dogs");
}
// ============================================
// CONDITIONAL STATEMENTS
// ============================================
// 20a. if / else if / else
const health = "healthy";
if (health === "healthy") {
console.log("Bunny is healthy");
} else if (health === "sick") {
console.log("Bunny is sick");
} else {
console.log("Unknown health status");
}
// 20b. switch statement
switch (health) {
case "healthy":
console.log("Bunny is healthy");
break;
case "sick":
console.log("Bunny is sick");
break;
default:
console.log("Unknown health status");
}
// 20c. Ternary operator
const healthMessage =
health === "healthy" ? "Bunny is healthy" : "Bunny is not healthy";
console.log(healthMessage);
// 21. Even or odd using ternary
function evenOrOdd(number) {
return number % 2 === 0 ? "even" : "odd";
}
console.log(evenOrOdd(4));
console.log(evenOrOdd(7));
console.log(evenOrOdd(0));
// ============================================
// LOOPS
// ============================================
// 22a. for loop: 0 through 9
for (let i = 0; i <= 9; i++) {
console.log("Number", i);
}
// 22b. while loop: 0 through 9
let number = 0;
while (number <= 9) {
console.log("Number", number);
number++;
}
// 23a. while loop countdown 9 to 1
let countdown = 9;
while (countdown >= 1) {
console.log(countdown);
countdown--;
}
// 23b. for loop countdown 9 to 1
for (let i = 9; i >= 1; i--) {
console.log(i);
}
// ============================================
// EXCEPTION HANDLING AND OPERATORS
// ============================================
// 24. Error handling
function sumBunniesWithValidation(blackBunnies, whiteBunnies) {
if (
typeof blackBunnies !== "number" ||
typeof whiteBunnies !== "number"
) {
throw new Error("Both arguments must be numbers");
}
return blackBunnies + whiteBunnies;
}
try {
console.log(sumBunniesWithValidation(10, "twenty"));
} catch (error) {
console.log(error.message);
}
// 25. Operators
let blackBunnies = 10;
let whiteBunnies = 5;
const totalBunnies = blackBunnies + whiteBunnies;
console.log(
"Are black and white bunnies equal?",
blackBunnies === whiteBunnies
);
console.log("Total bunnies:", totalBunnies);
console.log(
"Are there more than 12 bunnies?",
totalBunnies > 12
);
const answer = totalBunnies > 12 ? "Yes" : "No";
console.log(answer);
// ============================================
// BRAIN TEASERS
// ============================================
// Brain Teaser 1 — The quiet loop
let carrots = 3;
while (carrots) {
console.log("munch");
carrots--;
}
/*
Output:
munch
munch
munch
The loop stops when carrots becomes 0 because 0 is falsy.
If carrots-- were deleted, carrots would remain 3 forever,
so the loop would become an infinite loop.
*/
// Brain Teaser 2 — For loop
const bunnyList = [
"Lucy",
"Tom",
"Molly",
"Bella",
"Mario",
"Luigi"
];
for (let i = 0; i < bunnyList.length; i++) {
if (bunnyList[i].length > 4) {
console.log(bunnyList[i]);
}
}
// Brain Teaser 2 — While loop
let i = 0;
while (i < bunnyList.length) {
if (bunnyList[i].length > 4) {
console.log(bunnyList[i]);
}
i++;
}
// Brain Teaser 3 — Nested checkup
const nestedBunnies = [
["Lucy", "Tom"],
["Molly", "Bella"],
["Mario", "Luigi"]
];
let count = 1;
for (let i = 0; i < nestedBunnies.length; i++) {
for (let j = 0; j < nestedBunnies[i].length; j++) {
console.log(${count}. ${nestedBunnies[i][j]});
count++;
}
}
// Brain Teaser 4 — Loop + condition + function
function countHappyBunnies(bunnies) {
let happyCount = 0;
for (let i = 0; i < bunnies.length; i++) {
if (bunnies[i].isHappy === true) {
happyCount++;
}
}
return happyCount;
}
const happyBunnies = [
{ name: "Lucy", isHappy: true },
{ name: "Tom", isHappy: false },
{ name: "Molly", isHappy: true }
];
const happyCount = countHappyBunnies(happyBunnies);
const happinessMessage =
happyCount >= happyBunnies.length / 2
? "Most bunnies are happy"
: "Most bunnies are not happy";
console.log(happinessMessage);
// Brain Teaser 5 — Snippet A
for (let i = 0; i < 5; i++) {
console.log(i);
}
// Brain Teaser 5 — Snippet B (fixed)
let j = 0;
while (j < 5) {
console.log(j);
j++;
}
/*
When to pick for vs while:
Use a for loop when you know the number/range of repetitions,
and use a while loop when repetition mainly depends on a condition.
*/
// ============================================
// JAVASCRIPT ASSIGNMENTS
// ============================================
// ============================================
// VARIABLES
// ============================================
// 1. var, let, const
var bunny = "Lucy";
let dog = "Tom";
const cat = "Molly";
console.log(bunny);
console.log(dog);
console.log(cat);
// 2. Valid and invalid variable names
// 1bunny - invalid
// Correct version:
let bunny1;
// _bunny - valid
let _bunny = "Lucy";
// $bunny - valid
let $bunny = "Lucy";
// -bunny - invalid
// Correct version:
let bunnyName;
// @bunny - invalid
// Correct version:
let bunnyAt;
// bunnyName - valid
let validBunnyName = "Lucy";
console.log(bunny1, _bunny, $bunny, bunnyName, bunnyAt, validBunnyName);
// 3. Predicting var and let
console.log(pet);
var pet = "lucy";
// Output: undefined
// var is hoisted, so the variable declaration is known before execution,
// but its value is assigned only when that line is reached.
// console.log(animal);
// let animal = "tom";
// This causes a ReferenceError because let variables cannot be accessed
// before their declaration.
/*
4. Local and global variables
*/
let globalAnimal = "Bunny";
function animalName() {
let localAnimal = "Lucy";
console.log("Local variable:", localAnimal);
console.log("Global variable:", globalAnimal);
}
animalName();
// ============================================
// DATA TYPES
// ============================================
// 5. Object
const bunnyObject = {
name: "Lucy",
age: 3,
isHappy: true
};
console.log(bunnyObject.name);
console.log(bunnyObject.age);
console.log(bunnyObject.isHappy);
// 6. typeof
console.log(3.14, typeof 3.14);
console.log("Lucy", typeof "Lucy");
console.log(true, typeof true);
console.log(null, typeof null);
console.log(undefined, typeof undefined);
console.log(Symbol("Lucy"), typeof Symbol("Lucy"));
console.log({ name: "Lucy" }, typeof { name: "Lucy" });
console.log(["Lucy", "Tom"], typeof ["Lucy", "Tom"]);
// 7. Mixed data types
const mixedDataTypes = [
true,
25,
"Lucy",
null,
undefined,
{ name: "Tom" }
];
console.log(mixedDataTypes);
console.log("Length:", mixedDataTypes.length);
// ============================================
// FUNCTIONS
// ============================================
// 8. Function with no parameters
function sumBunnies() {
const blackBunnies = 10;
const whiteBunnies = 20;
return blackBunnies + whiteBunnies;
}
console.log(sumBunnies());
// 9. Function with parameters
function sumBunniesWithParameters(blackBunnies, whiteBunnies) {
return blackBunnies + whiteBunnies;
}
console.log(sumBunniesWithParameters(10, 20));
console.log(sumBunniesWithParameters(7, 3));
// 10a. Anonymous function
const anonymousSum = function (blackBunnies, whiteBunnies) {
return blackBunnies + whiteBunnies;
};
console.log(anonymousSum(10, 20));
// 10b. Arrow function
const arrowSum = (blackBunnies, whiteBunnies) => {
return blackBunnies + whiteBunnies;
};
console.log(arrowSum(10, 20));
// 11. IIFE
(function () {
const blackBunnies = 10;
const whiteBunnies = 20;
console.log("IIFE total:", blackBunnies + whiteBunnies);
})();
// ============================================
// ARRAYS
// ============================================
// 12. Array manipulation
const bunnyNames = [
"Lucy",
"Tom",
"Molly",
"Bella",
"Max",
"Charlie"
];
bunnyNames.push("Mario");
bunnyNames.unshift("Luigi");
// Remove Lucy
const lucyIndex = bunnyNames.indexOf("Lucy");
if (lucyIndex !== -1) {
bunnyNames.splice(lucyIndex, 1);
}
console.log(bunnyNames);
// 13. Array access
const bunnies = ["Lucy", "Tom", "Molly", "Bella"];
console.log("First item:", bunnies[0]);
console.log(
"Last item:",
bunnies[bunnies.length - 1]
);
console.log(
"Index of Tom:",
bunnies.indexOf("Tom")
);
const bunniesCopy = [...bunnies];
console.log("Copy:", bunniesCopy);
// 14. Loop through bunnies
for (let i = 0; i < bunnies.length; i++) {
console.log(
Bunny ${bunnies[i]} is scheduled for a checkup today.);
}
// 15. Nested arrays
const nestedArrays = [
["Lucy", "Tom"],
["Molly", "Bella"]
];
console.log(nestedArrays[0][0]); // Lucy
console.log(nestedArrays[1][1]); // Bella
for (let i = 0; i < nestedArrays.length; i++) {
for (let j = 0; j < nestedArrays[i].length; j++) {
console.log(nestedArrays[i][j]);
}
}
// ============================================
// JSON
// ============================================
// 16. JavaScript object -> JSON
const bunnyForJSON = {
name: "Lucy",
age: 3,
isHappy: true
};
const bunnyJSON = JSON.stringify(bunnyForJSON);
console.log(bunnyJSON);
// 17. JSON -> JavaScript object
let bunnyJSON2 = '{"name":"Lucy","age":3,"isHappy":true}';
const bunnyFromJSON = JSON.parse(bunnyJSON2);
console.log(bunnyFromJSON.name);
console.log(bunnyFromJSON.age);
// ============================================
// COMPARISON OPERATORS
// ============================================
// 18. ==, ===, !=, !==
let bunny_age = 3;
let dog_age = "3";
console.log(bunny_age == dog_age); // true
console.log(bunny_age === dog_age); // false
console.log(bunny_age != dog_age); // false
console.log(bunny_age !== dog_age); // true
// == compares values after type conversion,
// while === compares both value and type.
// 19. Compare array lengths
const bunniesForComparison = [
"Lucy",
"Tom",
"Molly"
];
const dogs = [
"Max",
"Buddy",
"Charlie",
"Rocky"
];
if (bunniesForComparison.length <= dogs.length) {
console.log("There are more dogs than bunnies");
} else {
console.log("There are more bunnies than dogs");
}
// ============================================
// CONDITIONAL STATEMENTS
// ============================================
// 20a. if / else if / else
const health = "healthy";
if (health === "healthy") {
console.log("Bunny is healthy");
} else if (health === "sick") {
console.log("Bunny is sick");
} else {
console.log("Unknown health status");
}
// 20b. switch statement
switch (health) {
case "healthy":
console.log("Bunny is healthy");
break;
case "sick":
console.log("Bunny is sick");
break;
default:
console.log("Unknown health status");
}
// 20c. Ternary operator
const healthMessage =
health === "healthy" ? "Bunny is healthy" : "Bunny is not healthy";
console.log(healthMessage);
// 21. Even or odd using ternary
function evenOrOdd(number) {
return number % 2 === 0 ? "even" : "odd";
}
console.log(evenOrOdd(4));
console.log(evenOrOdd(7));
console.log(evenOrOdd(0));
// ============================================
// LOOPS
// ============================================
// 22a. for loop: 0 through 9
for (let i = 0; i <= 9; i++) {
console.log("Number", i);
}
// 22b. while loop: 0 through 9
let number = 0;
while (number <= 9) {
console.log("Number", number);
number++;
}
// 23a. while loop countdown 9 to 1
let countdown = 9;
while (countdown >= 1) {
console.log(countdown);
countdown--;
}
// 23b. for loop countdown 9 to 1
for (let i = 9; i >= 1; i--) {
console.log(i);
}
// ============================================
// EXCEPTION HANDLING AND OPERATORS
// ============================================
// 24. Error handling
function sumBunniesWithValidation(blackBunnies, whiteBunnies) {
if (
typeof blackBunnies !== "number" ||
typeof whiteBunnies !== "number"
) {
throw new Error("Both arguments must be numbers");
}
return blackBunnies + whiteBunnies;
}
try {
console.log(sumBunniesWithValidation(10, "twenty"));
} catch (error) {
console.log(error.message);
}
// 25. Operators
let blackBunnies = 10;
let whiteBunnies = 5;
const totalBunnies = blackBunnies + whiteBunnies;
console.log(
"Are black and white bunnies equal?",
blackBunnies === whiteBunnies
);
console.log("Total bunnies:", totalBunnies);
console.log(
"Are there more than 12 bunnies?",
totalBunnies > 12
);
const answer = totalBunnies > 12 ? "Yes" : "No";
console.log(answer);
// ============================================
// BRAIN TEASERS
// ============================================
// Brain Teaser 1 — The quiet loop
let carrots = 3;
while (carrots) {
console.log("munch");
carrots--;
}
/*
Output:
munch
munch
munch
The loop stops when carrots becomes 0 because 0 is falsy.
If carrots-- were deleted, carrots would remain 3 forever,
so the loop would become an infinite loop.
*/
// Brain Teaser 2 — For loop
const bunnyList = [
"Lucy",
"Tom",
"Molly",
"Bella",
"Mario",
"Luigi"
];
for (let i = 0; i < bunnyList.length; i++) {
if (bunnyList[i].length > 4) {
console.log(bunnyList[i]);
}
}
// Brain Teaser 2 — While loop
let i = 0;
while (i < bunnyList.length) {
if (bunnyList[i].length > 4) {
console.log(bunnyList[i]);
}
i++;
}
// Brain Teaser 3 — Nested checkup
const nestedBunnies = [
["Lucy", "Tom"],
["Molly", "Bella"],
["Mario", "Luigi"]
];
let count = 1;
for (let i = 0; i < nestedBunnies.length; i++) {
for (let j = 0; j < nestedBunnies[i].length; j++) {
console.log(
${count}. ${nestedBunnies[i][j]});count++;
}
}
// Brain Teaser 4 — Loop + condition + function
function countHappyBunnies(bunnies) {
let happyCount = 0;
for (let i = 0; i < bunnies.length; i++) {
if (bunnies[i].isHappy === true) {
happyCount++;
}
}
return happyCount;
}
const happyBunnies = [
{ name: "Lucy", isHappy: true },
{ name: "Tom", isHappy: false },
{ name: "Molly", isHappy: true }
];
const happyCount = countHappyBunnies(happyBunnies);
const happinessMessage =
happyCount >= happyBunnies.length / 2
? "Most bunnies are happy"
: "Most bunnies are not happy";
console.log(happinessMessage);
// Brain Teaser 5 — Snippet A
for (let i = 0; i < 5; i++) {
console.log(i);
}
// Brain Teaser 5 — Snippet B (fixed)
let j = 0;
while (j < 5) {
console.log(j);
j++;
}
/*
When to pick for vs while:
Use a for loop when you know the number/range of repetitions,
and use a while loop when repetition mainly depends on a condition.
*/// ============================================
// JAVASCRIPT ASSIGNMENTS
// ============================================
// ============================================
// VARIABLES
// ============================================
// 1. var, let, const
var bunny = "Lucy";
let dog = "Tom";
const cat = "Molly";
console.log(bunny);
console.log(dog);
console.log(cat);
// 2. Valid and invalid variable names
// 1bunny - invalid
// Correct version:
let bunny1;
// _bunny - valid
let _bunny = "Lucy";
// $bunny - valid
let $bunny = "Lucy";
// -bunny - invalid
// Correct version:
let bunnyName;
// @bunny - invalid
// Correct version:
let bunnyAt;
// bunnyName - valid
let validBunnyName = "Lucy";
console.log(bunny1, _bunny, $bunny, bunnyName, bunnyAt, validBunnyName);
// 3. Predicting var and let
console.log(pet);
var pet = "lucy";
// Output: undefined
// var is hoisted, so the variable declaration is known before execution,
// but its value is assigned only when that line is reached.
// console.log(animal);
// let animal = "tom";
// This causes a ReferenceError because let variables cannot be accessed
// before their declaration.
/*
4. Local and global variables
*/
let globalAnimal = "Bunny";
function animalName() {
let localAnimal = "Lucy";
console.log("Local variable:", localAnimal);
console.log("Global variable:", globalAnimal);
}
animalName();
// ============================================
// DATA TYPES
// ============================================
// 5. Object
const bunnyObject = {
name: "Lucy",
age: 3,
isHappy: true
};
console.log(bunnyObject.name);
console.log(bunnyObject.age);
console.log(bunnyObject.isHappy);
// 6. typeof
console.log(3.14, typeof 3.14);
console.log("Lucy", typeof "Lucy");
console.log(true, typeof true);
console.log(null, typeof null);
console.log(undefined, typeof undefined);
console.log(Symbol("Lucy"), typeof Symbol("Lucy"));
console.log({ name: "Lucy" }, typeof { name: "Lucy" });
console.log(["Lucy", "Tom"], typeof ["Lucy", "Tom"]);
// 7. Mixed data types
const mixedDataTypes = [
true,
25,
"Lucy",
null,
undefined,
{ name: "Tom" }
];
console.log(mixedDataTypes);
console.log("Length:", mixedDataTypes.length);
// ============================================
// FUNCTIONS
// ============================================
// 8. Function with no parameters
function sumBunnies() {
const blackBunnies = 10;
const whiteBunnies = 20;
return blackBunnies + whiteBunnies;
}
console.log(sumBunnies());
// 9. Function with parameters
function sumBunniesWithParameters(blackBunnies, whiteBunnies) {
return blackBunnies + whiteBunnies;
}
console.log(sumBunniesWithParameters(10, 20));
console.log(sumBunniesWithParameters(7, 3));
// 10a. Anonymous function
const anonymousSum = function (blackBunnies, whiteBunnies) {
return blackBunnies + whiteBunnies;
};
console.log(anonymousSum(10, 20));
// 10b. Arrow function
const arrowSum = (blackBunnies, whiteBunnies) => {
return blackBunnies + whiteBunnies;
};
console.log(arrowSum(10, 20));
// 11. IIFE
(function () {
const blackBunnies = 10;
const whiteBunnies = 20;
console.log("IIFE total:", blackBunnies + whiteBunnies);
})();
// ============================================
// ARRAYS
// ============================================
// 12. Array manipulation
const bunnyNames = [
"Lucy",
"Tom",
"Molly",
"Bella",
"Max",
"Charlie"
];
bunnyNames.push("Mario");
bunnyNames.unshift("Luigi");
// Remove Lucy
const lucyIndex = bunnyNames.indexOf("Lucy");
if (lucyIndex !== -1) {
bunnyNames.splice(lucyIndex, 1);
}
console.log(bunnyNames);
// 13. Array access
const bunnies = ["Lucy", "Tom", "Molly", "Bella"];
console.log("First item:", bunnies[0]);
console.log(
"Last item:",
bunnies[bunnies.length - 1]
);
console.log(
"Index of Tom:",
bunnies.indexOf("Tom")
);
const bunniesCopy = [...bunnies];
console.log("Copy:", bunniesCopy);
// 14. Loop through bunnies
for (let i = 0; i < bunnies.length; i++) {
console.log(
Bunny ${bunnies[i]} is scheduled for a checkup today.);
}
// 15. Nested arrays
const nestedArrays = [
["Lucy", "Tom"],
["Molly", "Bella"]
];
console.log(nestedArrays[0][0]); // Lucy
console.log(nestedArrays[1][1]); // Bella
for (let i = 0; i < nestedArrays.length; i++) {
for (let j = 0; j < nestedArrays[i].length; j++) {
console.log(nestedArrays[i][j]);
}
}
// ============================================
// JSON
// ============================================
// 16. JavaScript object -> JSON
const bunnyForJSON = {
name: "Lucy",
age: 3,
isHappy: true
};
const bunnyJSON = JSON.stringify(bunnyForJSON);
console.log(bunnyJSON);
// 17. JSON -> JavaScript object
let bunnyJSON2 = '{"name":"Lucy","age":3,"isHappy":true}';
const bunnyFromJSON = JSON.parse(bunnyJSON2);
console.log(bunnyFromJSON.name);
console.log(bunnyFromJSON.age);
// ============================================
// COMPARISON OPERATORS
// ============================================
// 18. ==, ===, !=, !==
let bunny_age = 3;
let dog_age = "3";
console.log(bunny_age == dog_age); // true
console.log(bunny_age === dog_age); // false
console.log(bunny_age != dog_age); // false
console.log(bunny_age !== dog_age); // true
// == compares values after type conversion,
// while === compares both value and type.
// 19. Compare array lengths
const bunniesForComparison = [
"Lucy",
"Tom",
"Molly"
];
const dogs = [
"Max",
"Buddy",
"Charlie",
"Rocky"
];
if (bunniesForComparison.length <= dogs.length) {
console.log("There are more dogs than bunnies");
} else {
console.log("There are more bunnies than dogs");
}
// ============================================
// CONDITIONAL STATEMENTS
// ============================================
// 20a. if / else if / else
const health = "healthy";
if (health === "healthy") {
console.log("Bunny is healthy");
} else if (health === "sick") {
console.log("Bunny is sick");
} else {
console.log("Unknown health status");
}
// 20b. switch statement
switch (health) {
case "healthy":
console.log("Bunny is healthy");
break;
case "sick":
console.log("Bunny is sick");
break;
default:
console.log("Unknown health status");
}
// 20c. Ternary operator
const healthMessage =
health === "healthy" ? "Bunny is healthy" : "Bunny is not healthy";
console.log(healthMessage);
// 21. Even or odd using ternary
function evenOrOdd(number) {
return number % 2 === 0 ? "even" : "odd";
}
console.log(evenOrOdd(4));
console.log(evenOrOdd(7));
console.log(evenOrOdd(0));
// ============================================
// LOOPS
// ============================================
// 22a. for loop: 0 through 9
for (let i = 0; i <= 9; i++) {
console.log("Number", i);
}
// 22b. while loop: 0 through 9
let number = 0;
while (number <= 9) {
console.log("Number", number);
number++;
}
// 23a. while loop countdown 9 to 1
let countdown = 9;
while (countdown >= 1) {
console.log(countdown);
countdown--;
}
// 23b. for loop countdown 9 to 1
for (let i = 9; i >= 1; i--) {
console.log(i);
}
// ============================================
// EXCEPTION HANDLING AND OPERATORS
// ============================================
// 24. Error handling
function sumBunniesWithValidation(blackBunnies, whiteBunnies) {
if (
typeof blackBunnies !== "number" ||
typeof whiteBunnies !== "number"
) {
throw new Error("Both arguments must be numbers");
}
return blackBunnies + whiteBunnies;
}
try {
console.log(sumBunniesWithValidation(10, "twenty"));
} catch (error) {
console.log(error.message);
}
// 25. Operators
let blackBunnies = 10;
let whiteBunnies = 5;
const totalBunnies = blackBunnies + whiteBunnies;
console.log(
"Are black and white bunnies equal?",
blackBunnies === whiteBunnies
);
console.log("Total bunnies:", totalBunnies);
console.log(
"Are there more than 12 bunnies?",
totalBunnies > 12
);
const answer = totalBunnies > 12 ? "Yes" : "No";
console.log(answer);
// ============================================
// BRAIN TEASERS
// ============================================
// Brain Teaser 1 — The quiet loop
let carrots = 3;
while (carrots) {
console.log("munch");
carrots--;
}
/*
Output:
munch
munch
munch
The loop stops when carrots becomes 0 because 0 is falsy.
If carrots-- were deleted, carrots would remain 3 forever,
so the loop would become an infinite loop.
*/
// Brain Teaser 2 — For loop
const bunnyList = [
"Lucy",
"Tom",
"Molly",
"Bella",
"Mario",
"Luigi"
];
for (let i = 0; i < bunnyList.length; i++) {
if (bunnyList[i].length > 4) {
console.log(bunnyList[i]);
}
}
// Brain Teaser 2 — While loop
let i = 0;
while (i < bunnyList.length) {
if (bunnyList[i].length > 4) {
console.log(bunnyList[i]);
}
i++;
}
// Brain Teaser 3 — Nested checkup
const nestedBunnies = [
["Lucy", "Tom"],
["Molly", "Bella"],
["Mario", "Luigi"]
];
let count = 1;
for (let i = 0; i < nestedBunnies.length; i++) {
for (let j = 0; j < nestedBunnies[i].length; j++) {
console.log(
${count}. ${nestedBunnies[i][j]});count++;
}
}
// Brain Teaser 4 — Loop + condition + function
function countHappyBunnies(bunnies) {
let happyCount = 0;
for (let i = 0; i < bunnies.length; i++) {
if (bunnies[i].isHappy === true) {
happyCount++;
}
}
return happyCount;
}
const happyBunnies = [
{ name: "Lucy", isHappy: true },
{ name: "Tom", isHappy: false },
{ name: "Molly", isHappy: true }
];
const happyCount = countHappyBunnies(happyBunnies);
const happinessMessage =
happyCount >= happyBunnies.length / 2
? "Most bunnies are happy"
: "Most bunnies are not happy";
console.log(happinessMessage);
// Brain Teaser 5 — Snippet A
for (let i = 0; i < 5; i++) {
console.log(i);
}
// Brain Teaser 5 — Snippet B (fixed)
let j = 0;
while (j < 5) {
console.log(j);
j++;
}
/*
When to pick for vs while:
Use a for loop when you know the number/range of repetitions,
and use a while loop when repetition mainly depends on a condition.
*/