JavaScript-Fundamentals/040-fn-expression.js at main · FullStack-Flow/JavaScript-Fundamentals · GitHub

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// 1: RETURN VALUES
// function add(a, b) {
// return a + b;
// }

// const result = add(5, 3);
// console.log(result); // 8

// 2: FUNCTIONS WITHOUT RETURN
// function greet(name) {
// console.log("Hello, " + name);
// }

// const greeting = greet("Sarah");
// console.log(greeting); // undefined

// 3: RETURN STOPS EXECUTION
functioncheckAge(age){
if(age<18){
return"Too young";
}
return"Welcome!";
console.log("This will never run");// Unreachable code
}

constmessage=checkAge(15);
console.log(message);// "Too young"

// 4: RETURNING DIFFERENT DATA TYPES
// Returning a boolean
// function isEven(number) {
// return number % 2 === 0;
// }

// console.log(isEven(4)); // true

// Returning an array
// function getColors() {
// return ["red", "green", "blue"];
// }

// const colors = getColors();
// console.log(colors[0]); // "red"

// // Returning an object
// function createUser(name, age) {
// return {
// name: name,
// age: age,
// active: true
// };
// }

// const user = createUser("John", 25);
// console.log(user.name); // "John"

// 5: FUNCTION EXPRESSIONS
// const sayHello = function() {
// console.log("Hello!");
// };

// sayHello(); // "Hello!"

// 6: DECLARATION VS EXPRESSION
// This works - function declaration
greet();

functiongreet(){
console.log("Hello from declaration!");
}

// This causes an error - function expression
sayGoodbye();// Error: Cannot access 'sayGoodbye' before initialization

constsayGoodbye=function(){
console.log("Goodbye from expression!");
};

// 7: NAMED FUNCTION EXPRESSIONS
constfactorial=functioncalculateFactorial(n){
if(n<=1)return1;
returnn*calculateFactorial(n-1);
};

console.log(factorial(5));// 120

// 8: PRACTICAL EXAMPLE
constcalculateDiscount=function(price,discountPercent){
if(price<=0){
return0;
}

constdiscount=price*(discountPercent/100);
constfinalPrice=price-discount;

returnfinalPrice;
};

constoriginalPrice=100;
constdiscountedPrice=calculateDiscount(originalPrice,20);

console.log("Original: $"+originalPrice);// "Original: $100"
console.log("After discount: $"+discountedPrice);// "After discount: $80"

// 9: WHEN TO USE EACH STYLE
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// 1: RETURN VALUES
// function add(a, b) {
// return a + b;
// }

// const result = add(5, 3);
// console.log(result); // 8

// 2: FUNCTIONS WITHOUT RETURN
// function greet(name) {
// console.log("Hello, " + name);
// }

// const greeting = greet("Sarah");
// console.log(greeting); // undefined

// 3: RETURN STOPS EXECUTION
functioncheckAge(age){
if(age<18){
return"Too young";
}
return"Welcome!";
console.log("This will never run");// Unreachable code
}

constmessage=checkAge(15);
console.log(message);// "Too young"

// 4: RETURNING DIFFERENT DATA TYPES
// Returning a boolean
// function isEven(number) {
// return number % 2 === 0;
// }

// console.log(isEven(4)); // true

// Returning an array
// function getColors() {
// return ["red", "green", "blue"];
// }

// const colors = getColors();
// console.log(colors[0]); // "red"

// // Returning an object
// function createUser(name, age) {
// return {
// name: name,
// age: age,
// active: true
// };
// }

// const user = createUser("John", 25);
// console.log(user.name); // "John"

// 5: FUNCTION EXPRESSIONS
// const sayHello = function() {
// console.log("Hello!");
// };

// sayHello(); // "Hello!"

// 6: DECLARATION VS EXPRESSION
// This works - function declaration
greet();

functiongreet(){
console.log("Hello from declaration!");
}

// This causes an error - function expression
sayGoodbye();// Error: Cannot access 'sayGoodbye' before initialization

constsayGoodbye=function(){
console.log("Goodbye from expression!");
};

// 7: NAMED FUNCTION EXPRESSIONS
constfactorial=functioncalculateFactorial(n){
if(n<=1)return1;
returnn*calculateFactorial(n-1);
};

console.log(factorial(5));// 120

// 8: PRACTICAL EXAMPLE
constcalculateDiscount=function(price,discountPercent){
if(price<=0){
return0;
}

constdiscount=price*(discountPercent/100);
constfinalPrice=price-discount;

returnfinalPrice;
};

constoriginalPrice=100;
constdiscountedPrice=calculateDiscount(originalPrice,20);

console.log("Original: $"+originalPrice);// "Original: $100"
console.log("After discount: $"+discountedPrice);// "After discount: $80"

// 9: WHEN TO USE EACH STYLE
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// 1: RETURN VALUES
// function add(a, b) {
// return a + b;
// }

// const result = add(5, 3);
// console.log(result); // 8

// 2: FUNCTIONS WITHOUT RETURN
// function greet(name) {
// console.log("Hello, " + name);
// }

// const greeting = greet("Sarah");
// console.log(greeting); // undefined

// 3: RETURN STOPS EXECUTION
functioncheckAge(age){
if(age<18){
return"Too young";
}
return"Welcome!";
console.log("This will never run");// Unreachable code
}

constmessage=checkAge(15);
console.log(message);// "Too young"

// 4: RETURNING DIFFERENT DATA TYPES
// Returning a boolean
// function isEven(number) {
// return number % 2 === 0;
// }

// console.log(isEven(4)); // true

// Returning an array
// function getColors() {
// return ["red", "green", "blue"];
// }

// const colors = getColors();
// console.log(colors[0]); // "red"

// // Returning an object
// function createUser(name, age) {
// return {
// name: name,
// age: age,
// active: true
// };
// }

// const user = createUser("John", 25);
// console.log(user.name); // "John"

// 5: FUNCTION EXPRESSIONS
// const sayHello = function() {
// console.log("Hello!");
// };

// sayHello(); // "Hello!"

// 6: DECLARATION VS EXPRESSION
// This works - function declaration
greet();

functiongreet(){
console.log("Hello from declaration!");
}

// This causes an error - function expression
sayGoodbye();// Error: Cannot access 'sayGoodbye' before initialization

constsayGoodbye=function(){
console.log("Goodbye from expression!");
};

// 7: NAMED FUNCTION EXPRESSIONS
constfactorial=functioncalculateFactorial(n){
if(n<=1)return1;
returnn*calculateFactorial(n-1);
};

console.log(factorial(5));// 120

// 8: PRACTICAL EXAMPLE
constcalculateDiscount=function(price,discountPercent){
if(price<=0){
return0;
}

constdiscount=price*(discountPercent/100);
constfinalPrice=price-discount;

returnfinalPrice;
};

constoriginalPrice=100;
constdiscountedPrice=calculateDiscount(originalPrice,20);

console.log("Original: $"+originalPrice);// "Original: $100"
console.log("After discount: $"+discountedPrice);// "After discount: $80"

// 9: WHEN TO USE EACH STYLE
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// 1: RETURN VALUES
// function add(a, b) {
// return a + b;
// }

// const result = add(5, 3);
// console.log(result); // 8

// 2: FUNCTIONS WITHOUT RETURN
// function greet(name) {
// console.log("Hello, " + name);
// }

// const greeting = greet("Sarah");
// console.log(greeting); // undefined

// 3: RETURN STOPS EXECUTION
functioncheckAge(age){
if(age<18){
return"Too young";
}
return"Welcome!";
console.log("This will never run");// Unreachable code
}

constmessage=checkAge(15);
console.log(message);// "Too young"

// 4: RETURNING DIFFERENT DATA TYPES
// Returning a boolean
// function isEven(number) {
// return number % 2 === 0;
// }

// console.log(isEven(4)); // true

// Returning an array
// function getColors() {
// return ["red", "green", "blue"];
// }

// const colors = getColors();
// console.log(colors[0]); // "red"

// // Returning an object
// function createUser(name, age) {
// return {
// name: name,
// age: age,
// active: true
// };
// }

// const user = createUser("John", 25);
// console.log(user.name); // "John"

// 5: FUNCTION EXPRESSIONS
// const sayHello = function() {
// console.log("Hello!");
// };

// sayHello(); // "Hello!"

// 6: DECLARATION VS EXPRESSION
// This works - function declaration
greet();

functiongreet(){
console.log("Hello from declaration!");
}

// This causes an error - function expression
sayGoodbye();// Error: Cannot access 'sayGoodbye' before initialization

constsayGoodbye=function(){
console.log("Goodbye from expression!");
};

// 7: NAMED FUNCTION EXPRESSIONS
constfactorial=functioncalculateFactorial(n){
if(n<=1)return1;
returnn*calculateFactorial(n-1);
};

console.log(factorial(5));// 120

// 8: PRACTICAL EXAMPLE
constcalculateDiscount=function(price,discountPercent){
if(price<=0){
return0;
}

constdiscount=price*(discountPercent/100);
constfinalPrice=price-discount;

returnfinalPrice;
};

constoriginalPrice=100;
constdiscountedPrice=calculateDiscount(originalPrice,20);

console.log("Original: $"+originalPrice);// "Original: $100"
console.log("After discount: $"+discountedPrice);// "After discount: $80"

// 9: WHEN TO USE EACH STYLE
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// 1: RETURN VALUES
// function add(a, b) {
// return a + b;
// }

// const result = add(5, 3);
// console.log(result); // 8

// 2: FUNCTIONS WITHOUT RETURN
// function greet(name) {
// console.log("Hello, " + name);
// }

// const greeting = greet("Sarah");
// console.log(greeting); // undefined

// 3: RETURN STOPS EXECUTION
functioncheckAge(age){
if(age<18){
return"Too young";
}
return"Welcome!";
console.log("This will never run");// Unreachable code
}

constmessage=checkAge(15);
console.log(message);// "Too young"

// 4: RETURNING DIFFERENT DATA TYPES
// Returning a boolean
// function isEven(number) {
// return number % 2 === 0;
// }

// console.log(isEven(4)); // true

// Returning an array
// function getColors() {
// return ["red", "green", "blue"];
// }

// const colors = getColors();
// console.log(colors[0]); // "red"

// // Returning an object
// function createUser(name, age) {
// return {
// name: name,
// age: age,
// active: true
// };
// }

// const user = createUser("John", 25);
// console.log(user.name); // "John"

// 5: FUNCTION EXPRESSIONS
// const sayHello = function() {
// console.log("Hello!");
// };

// sayHello(); // "Hello!"

// 6: DECLARATION VS EXPRESSION
// This works - function declaration
greet();

functiongreet(){
console.log("Hello from declaration!");
}

// This causes an error - function expression
sayGoodbye();// Error: Cannot access 'sayGoodbye' before initialization

constsayGoodbye=function(){
console.log("Goodbye from expression!");
};

// 7: NAMED FUNCTION EXPRESSIONS
constfactorial=functioncalculateFactorial(n){
if(n<=1)return1;
returnn*calculateFactorial(n-1);
};

console.log(factorial(5));// 120

// 8: PRACTICAL EXAMPLE
constcalculateDiscount=function(price,discountPercent){
if(price<=0){
return0;
}

constdiscount=price*(discountPercent/100);
constfinalPrice=price-discount;

returnfinalPrice;
};

constoriginalPrice=100;
constdiscountedPrice=calculateDiscount(originalPrice,20);

console.log("Original: $"+originalPrice);// "Original: $100"
console.log("After discount: $"+discountedPrice);// "After discount: $80"

// 9: WHEN TO USE EACH STYLE
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// 1: RETURN VALUES
// function add(a, b) {
// return a + b;
// }

// const result = add(5, 3);
// console.log(result); // 8

// 2: FUNCTIONS WITHOUT RETURN
// function greet(name) {
// console.log("Hello, " + name);
// }

// const greeting = greet("Sarah");
// console.log(greeting); // undefined

// 3: RETURN STOPS EXECUTION
functioncheckAge(age){
if(age<18){
return"Too young";
}
return"Welcome!";
console.log("This will never run");// Unreachable code
}

constmessage=checkAge(15);
console.log(message);// "Too young"

// 4: RETURNING DIFFERENT DATA TYPES
// Returning a boolean
// function isEven(number) {
// return number % 2 === 0;
// }

// console.log(isEven(4)); // true

// Returning an array
// function getColors() {
// return ["red", "green", "blue"];
// }

// const colors = getColors();
// console.log(colors[0]); // "red"

// // Returning an object
// function createUser(name, age) {
// return {
// name: name,
// age: age,
// active: true
// };
// }

// const user = createUser("John", 25);
// console.log(user.name); // "John"

// 5: FUNCTION EXPRESSIONS
// const sayHello = function() {
// console.log("Hello!");
// };

// sayHello(); // "Hello!"

// 6: DECLARATION VS EXPRESSION
// This works - function declaration
greet();

functiongreet(){
console.log("Hello from declaration!");
}

// This causes an error - function expression
sayGoodbye();// Error: Cannot access 'sayGoodbye' before initialization

constsayGoodbye=function(){
console.log("Goodbye from expression!");
};

// 7: NAMED FUNCTION EXPRESSIONS
constfactorial=functioncalculateFactorial(n){
if(n<=1)return1;
returnn*calculateFactorial(n-1);
};

console.log(factorial(5));// 120

// 8: PRACTICAL EXAMPLE
constcalculateDiscount=function(price,discountPercent){
if(price<=0){
return0;
}

constdiscount=price*(discountPercent/100);
constfinalPrice=price-discount;

returnfinalPrice;
};

constoriginalPrice=100;
constdiscountedPrice=calculateDiscount(originalPrice,20);

console.log("Original: $"+originalPrice);// "Original: $100"
console.log("After discount: $"+discountedPrice);// "After discount: $80"

// 9: WHEN TO USE EACH STYLE
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// 1: RETURN VALUES
// function add(a, b) {
// return a + b;
// }

// const result = add(5, 3);
// console.log(result); // 8

// 2: FUNCTIONS WITHOUT RETURN
// function greet(name) {
// console.log("Hello, " + name);
// }

// const greeting = greet("Sarah");
// console.log(greeting); // undefined

// 3: RETURN STOPS EXECUTION
functioncheckAge(age){
if(age<18){
return"Too young";
}
return"Welcome!";
console.log("This will never run");// Unreachable code
}

constmessage=checkAge(15);
console.log(message);// "Too young"

// 4: RETURNING DIFFERENT DATA TYPES
// Returning a boolean
// function isEven(number) {
// return number % 2 === 0;
// }

// console.log(isEven(4)); // true

// Returning an array
// function getColors() {
// return ["red", "green", "blue"];
// }

// const colors = getColors();
// console.log(colors[0]); // "red"

// // Returning an object
// function createUser(name, age) {
// return {
// name: name,
// age: age,
// active: true
// };
// }

// const user = createUser("John", 25);
// console.log(user.name); // "John"

// 5: FUNCTION EXPRESSIONS
// const sayHello = function() {
// console.log("Hello!");
// };

// sayHello(); // "Hello!"

// 6: DECLARATION VS EXPRESSION
// This works - function declaration
greet();

functiongreet(){
console.log("Hello from declaration!");
}

// This causes an error - function expression
sayGoodbye();// Error: Cannot access 'sayGoodbye' before initialization

constsayGoodbye=function(){
console.log("Goodbye from expression!");
};

// 7: NAMED FUNCTION EXPRESSIONS
constfactorial=functioncalculateFactorial(n){
if(n<=1)return1;
returnn*calculateFactorial(n-1);
};

console.log(factorial(5));// 120

// 8: PRACTICAL EXAMPLE
constcalculateDiscount=function(price,discountPercent){
if(price<=0){
return0;
}

constdiscount=price*(discountPercent/100);
constfinalPrice=price-discount;

returnfinalPrice;
};

constoriginalPrice=100;
constdiscountedPrice=calculateDiscount(originalPrice,20);

console.log("Original: $"+originalPrice);// "Original: $100"
console.log("After discount: $"+discountedPrice);// "After discount: $80"

// 9: WHEN TO USE EACH STYLE
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// 1: RETURN VALUES
// function add(a, b) {
// return a + b;
// }

// const result = add(5, 3);
// console.log(result); // 8

// 2: FUNCTIONS WITHOUT RETURN
// function greet(name) {
// console.log("Hello, " + name);
// }

// const greeting = greet("Sarah");
// console.log(greeting); // undefined

// 3: RETURN STOPS EXECUTION
functioncheckAge(age){
if(age<18){
return"Too young";
}
return"Welcome!";
console.log("This will never run");// Unreachable code
}

constmessage=checkAge(15);
console.log(message);// "Too young"

// 4: RETURNING DIFFERENT DATA TYPES
// Returning a boolean
// function isEven(number) {
// return number % 2 === 0;
// }

// console.log(isEven(4)); // true

// Returning an array
// function getColors() {
// return ["red", "green", "blue"];
// }

// const colors = getColors();
// console.log(colors[0]); // "red"

// // Returning an object
// function createUser(name, age) {
// return {
// name: name,
// age: age,
// active: true
// };
// }

// const user = createUser("John", 25);
// console.log(user.name); // "John"

// 5: FUNCTION EXPRESSIONS
// const sayHello = function() {
// console.log("Hello!");
// };

// sayHello(); // "Hello!"

// 6: DECLARATION VS EXPRESSION
// This works - function declaration
greet();

functiongreet(){
console.log("Hello from declaration!");
}

// This causes an error - function expression
sayGoodbye();// Error: Cannot access 'sayGoodbye' before initialization

constsayGoodbye=function(){
console.log("Goodbye from expression!");
};

// 7: NAMED FUNCTION EXPRESSIONS
constfactorial=functioncalculateFactorial(n){
if(n<=1)return1;
returnn*calculateFactorial(n-1);
};

console.log(factorial(5));// 120

// 8: PRACTICAL EXAMPLE
constcalculateDiscount=function(price,discountPercent){
if(price<=0){
return0;
}

constdiscount=price*(discountPercent/100);
constfinalPrice=price-discount;

returnfinalPrice;
};

constoriginalPrice=100;
constdiscountedPrice=calculateDiscount(originalPrice,20);

console.log("Original: $"+originalPrice);// "Original: $100"
console.log("After discount: $"+discountedPrice);// "After discount: $80"

// 9: WHEN TO USE EACH STYLE