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10. Functions – JavaScript Programs
1. Function Declaration (Named Function)
Program 1: Simple Function
<script>
function greet() {
document.write("Hello World");
}
greet();
</script>
Program 2: Function with Parameters
<script>
function add(a, b) {
return a + b;
}
document.write(add(10, 20));
</script>
Program 3: Function with Conditional Logic
<script>
function isEven(n) {
return n % 2 === 0;
}
document.write(isEven(6));
</script>
2. Function Expression
Program 1: Anonymous Function
<script>
let greet = function () {
document.write("Hello from Function Expression");
};
greet();
</script>
Program 2: Function Expression with Parameters
<script>
let multiply = function (a, b) {
return a * b;
};
document.write(multiply(4, 5));
</script>
Program 3: Conditional Function Expression
<script>
let checkAge = function (age) {
return age >= 18 ? "Adult" : "Minor";
};
document.write(checkAge(20));
</script>
3. Arrow Function
Program 1: Simple Arrow Function
<script>
let greet = () => document.write("Hello Arrow Function");
greet();
</script>
Program 2: Arrow Function with Parameters
<script>
let square = n => n * n;
document.write(square(5));
</script>
Program 3: Arrow Function with Multiple Parameters
<script>
let sum = (a, b) => a + b;
document.write(sum(10, 15));
</script>
4. Function with Default Parameters
Program 1: Default Value
<script>
function greet(name = "Guest") {
document.write("Hello " + name);
}
greet();
</script>
Program 2: Calculator with Default Values
<script>
function add(a = 0, b = 0) {
return a + b;
}
document.write(add(5));
</script>
Program 3: Default Parameter with Condition
<script>
function discount(price, rate = 10) {
return price - (price * rate / 100);
}
document.write(discount(100));
</script>
5. Rest Parameter Function
Program 1: Sum of Multiple Numbers
<script>
function sum(...nums) {
let total = 0;
for (let n of nums) total += n;
return total;
}
document.write(sum(1, 2, 3, 4));
</script>
Program 2: Count Arguments
<script>
function countArgs(...args) {
return args.length;
}
document.write(countArgs(10, 20, 30));
</script>
Program 3: Find Maximum
<script>
function max(...nums) {
return Math.max(...nums);
}
document.write(max(5, 12, 8));
</script>
6. Callback Function
Program 1: Basic Callback
<script>
function greet(name, callback) {
callback(name);
}
greet("Boby", function(n) {
document.write("Hello " + n);
});
</script>
Program 2: Callback with Calculation
<script>
function calculate(a, b, operation) {
return operation(a, b);
}
document.write(calculate(5, 3, (x, y) => x + y));
</script>
Program 3: Callback with Array
<script>
let numbers = [1, 2, 3];
numbers.forEach(function(n) {
document.write(n + " ");
});
</script>
7. Recursive Function
Program 1: Factorial
<script>
function factorial(n) {
if (n === 1) return 1;
return n * factorial(n - 1);
}
document.write(factorial(5));
</script>
Program 2: Fibonacci
<script>
function fib(n) {
if (n <= 1) return n;
return fib(n - 1) + fib(n - 2);
}
document.write(fib(6));
</script>
Program 3: Sum of Numbers
<script>
function sum(n) {
if (n === 0) return 0;
return n + sum(n - 1);
}
document.write(sum(5));
</script>
8. IIFE (Immediately Invoked Function Expression)
Program 1: Basic IIFE
<script>
(function() {
document.write("IIFE Executed");
})();
</script>
Program 2: IIFE with Parameters
<script>
(function(name) {
document.write("Hello " + name);
})("JavaScript");
</script>
Program 3: IIFE with Calculation
<script>
let result = (function(a, b) {
return a + b;
})(10, 20);
document.write(result);
</script>
10. Other programs for practice.
Program 1. Print a Number
<script>
function printNum(n) { return n; }
const printNumArrow = n => n;
document.write(printNum(10) + "<br>");
document.write(printNumArrow(10));
</script>
Program 2. Add Two Numbers
<script>
function add(a, b) { return a + b; }
const addArrow = (a, b) => a + b;
document.write(add(5, 7) + "<br>");
document.write(addArrow(5, 7));
</script>
Program 3. Subtract Two Numbers
<script>
function subtract(a, b) { return a - b; }
const subtractArrow = (a, b) => a - b;
document.write(subtract(10, 4));
</script>
Program 4. Multiply Two Numbers
<script>
function multiply(a, b) { return a * b; }
const multiplyArrow = (a, b) => a * b;
document.write(multiply(3, 4));
</script>
Program 5. Divide Two Numbers
<script>
function divide(a, b) { return a / b; }
const divideArrow = (a, b) => a / b;
document.write(divide(20, 5));
</script>
Program 6. Check Even or Odd
<script>
function evenOdd(n) {
return n % 2 === 0 ? "Even" : "Odd";
}
const evenOddArrow = n => n % 2 === 0 ? "Even" : "Odd";
document.write(evenOdd(7));
</script>
Program 7. Check Positive / Negative / Zero
<script>
function checkNum(n) {
if (n > 0) return "Positive";
else if (n < 0) return "Negative";
else return "Zero";
}
const checkNumArrow = n =>
n > 0 ? "Positive" : n < 0 ? "Negative" : "Zero";
document.write(checkNum(-5));
</script>
Program 8. Largest of Two Numbers
<script>
function maxTwo(a, b) {
return a > b ? a : b;
}
const maxTwoArrow = (a, b) => a > b ? a : b;
document.write(maxTwo(10, 20));
</script>
Program 9. Largest of Three Numbers
<script>
function maxThree(a, b, c) {
if (a >= b && a >= c) return a;
else if (b >= c) return b;
else return c;
}
const maxThreeArrow = (a, b, c) =>
a >= b && a >= c ? a : b >= c ? b : c;
document.write(maxThree(10, 30, 20));
</script>
Program 10. Voting Eligibility
<script>
function canVote(age) {
return age >= 18 ? "Eligible" : "Not Eligible";
}
const canVoteArrow = age => age >= 18 ? "Eligible" : "Not Eligible";
document.write(canVote(17));
</script>
Program 11. Print 1 to N
<script>
function print1toN(n) {
let i;
for (i = 1; i <= n; i++) document.write(i + " ");
}
const print1toNArrow = n => {
for (let i = 1; i <= n; i++) document.write(i + " ");
};
print1toN(5);
</script>
Program 12. Print N to 1
<script>
function printNto1(n) {
while (n >= 1) {
document.write(n + " ");
n--;
}
}
const printNto1Arrow = n => {
while (n >= 1) document.write(n-- + " ");
};
printNto1(5);
</script>
Program 13. Sum of First N Natural Numbers
<script>
function sumN(n) {
let sum = 0;
for (let i = 1; i <= n; i++) sum += i;
return sum;
}
const sumNArrow = n => {
let s = 0;
for (let i = 1; i <= n; i++) s += i;
return s;
};
document.write(sumN(5));
</script>
Program 14. Multiplication Table
<script>
function table(n) {
for (let i = 1; i <= 10; i++)
document.write(n + " x " + i + " = " + (n*i) + "<br>");
}
const tableArrow = n => table(n);
table(4);
</script>
Program 15. Factorial of a Number
<script>
function factorial(n) {
let f = 1;
for (let i = 1; i <= n; i++) f *= i;
return f;
}
const factorialArrow = n => {
let f = 1;
for (let i = 1; i <= n; i++) f *= i;
return f;
};
document.write(factorial(5));
</script>
Program 16. Fibonacci Series (N terms)
<script>
function fibonacci(n) {
let a = 0, b = 1;
for (let i = 1; i <= n; i++) {
document.write(a + " ");
let c = a + b;
a = b; b = c;
}
}
const fibonacciArrow = n => fibonacci(n);
fibonacci(6);
</script>
Program 17. Reverse a Number
<script>
function reverseNum(n) {
let rev = 0;
while (n > 0) {
rev = rev * 10 + (n % 10);
n = Math.floor(n / 10);
}
return rev;
}
const reverseNumArrow = n => reverseNum(n);
document.write(reverseNum(123));
</script>
Program 18. Palindrome Number
<script>
function isPalindrome(n) {
return n === reverseNum(n) ? "Palindrome" : "Not Palindrome";
}
const isPalindromeArrow = n =>
n === reverseNum(n) ? "Palindrome" : "Not Palindrome";
document.write(isPalindrome(121));
</script>
Program 19. Count Digits
<script>
function countDigits(n) {
let count = 0;
do {
count++;
n = Math.floor(n / 10);
} while (n > 0);
return count;
}
const countDigitsArrow = n => countDigits(n);
document.write(countDigits(12345));
</script>
Program 20. Prime Number Check
<script>
function isPrime(n) {
if (n <= 1) return "Not Prime";
for (let i = 2; i <= Math.sqrt(n); i++)
if (n % i === 0) return "Not Prime";
return "Prime";
}
const isPrimeArrow = n => isPrime(n);
document.write(isPrime(7));
</script>
Program 21. Leap Year
<script>
function leapYear(y) {
return (y % 4 === 0 && y % 100 !== 0) || y % 400 === 0
? "Leap Year" : "Not Leap Year";
}
const leapYearArrow = y => leapYear(y);
document.write(leapYear(2024));
</script>
Program 22. Calculator using switch
<script>
function calc(a, b, op) {
switch (op) {
case '+': return a + b;
case '-': return a - b;
case '*': return a * b;
case '/': return a / b;
default: return "Invalid";
}
}
const calcArrow = (a, b, op) => calc(a, b, op);
document.write(calc(10, 5, '*'));
</script>
Program 23. Square of Number
<script>
function square(n) { return n * n; }
const squareArrow = n => n * n;
document.write(square(6));
</script>
Program 24. Cube of Number
<script>
function cube(n) { return n * n * n; }
const cubeArrow = n => n * n * n;
document.write(cube(4));
</script>
Program 25. Celsius to Fahrenheit
<script>
function cToF(c) { return (c * 9/5) + 32; }
const cToFArrow = c => (c * 9/5) + 32;
document.write(cToF(25));
</script>
Program 26. Fahrenheit to Celsius
<script>
function fToC(f) { return (f - 32) * 5/9; }
const fToCArrow = f => (f - 32) * 5/9;
document.write(fToC(77));
</script>
Program 27. Area of Circle
<script>
function areaCircle(r) { return 3.14 * r * r; }
const areaCircleArrow = r => 3.14 * r * r;
document.write(areaCircle(5));
</script>
Program 28. Area of Rectangle
<script>
function areaRect(l, w) { return l * w; }
const areaRectArrow = (l, w) => l * w;
document.write(areaRect(10, 4));
</script>
Program 29. Area of Triangle
<script>
function areaTri(b, h) { return 0.5 * b * h; }
const areaTriArrow = (b, h) => 0.5 * b * h;
document.write(areaTri(8, 5));
</script>
Program 30. Simple Loop Counter
<script>
function countDown(n) {
while (n > 0) {
document.write(n + " ");
n--;
}
}
const countDownArrow = n => countDown(n);
countDown(5);
</script>