UNIT I – Basics of JavaScript Programming
4 Marks Questions
Q1. Write a JavaScript program to print even numbers from 1 to 10 using a loop.
<!DOCTYPE html>
<html>
<body>
<h3>Even Numbers from 1 to 10</h3>
<script>
for (let i = 1; i <= 10; i++) {
if (i % 2 === 0) {
document.write(i + "<br>");
}
}
</script>
</body>
</html>
Output :-
2
4
6
8
10
Q2. Differentiate between if, if...else, and switch statements with syntax.
Statement Description Syntax Example
if Executes code if condition is true if(condition){...}
if...else Executes one block if true, another if false if(condition){...} else {...}
switch Selects one case based on a value switch(value){ case ... }
Example:
// if
if (x > 0) console.log("Positive");
// if...else
if (x % 2 === 0) console.log("Even");
else console.log("Odd");
// switch
switch(day) {
case 1: console.log("Monday"); break;
case 2: console.log("Tuesday"); break;
default: console.log("Other Day");
}
Output :-
Positive
Even
Tuesday
Q3. Key features of JavaScript (with examples):
1. Lightweight – Runs quickly in browsers.
2. Cross-platform – Works on all OS.
3. Object-oriented – Uses objects and methods.
4. Event-driven – Responds to user actions.
5. Functional – Functions are first-class citizens.
Example:
document.getElementById("btn").onclick = function() {
alert("Button Clicked!");
};
Output :-
(When you click the button, an alert pops up saying "Button Clicked!")
Q4. Create car object, update a property, delete a property.
<script>
let car = {
brand: "Toyota",
model: "Corolla",
year: 2020,
display: function() {
document.write(this.brand + " " + this.model);
}
};
car.year = 2022; // update
delete car.model; // delete
car.display();
</script>
Output :-
Honda undefined
Q5. Largest of three numbers using if...else if...else:
<script>
let a = 10, b = 20, c = 15;
if(a > b && a > c) document.write(a + " is largest");
else if(b > a && b > c) document.write(b + " is largest");
else document.write(c + " is largest");
</script>
Output :-
20 is largest
Q6. Even or Odd using if...else:
<script>
let num = 5;
if(num % 2 === 0) document.write("Even");
else document.write("Odd");
</script>
Output :- Odd
Q7. Syntax of switch with example:
switch(expression) {
case value1:
// code
break;
case value2:
// code
break;
default:
// code
}
Example:
let day = 2;
switch(day) {
case 1: console.log("Monday"); break;
case 2: console.log("Tuesday"); break;
default: console.log("Other day");
}
Output :- Tuesday
Q8. Largest of three numbers using nested if...else:
<script>
let a = 5, b = 8, c = 3;
if(a > b) {
if(a > c) document.write(a);
else document.write(c);
} else {
if(b > c) document.write(b);
else document.write(c);
}
</script>
Output :- 8
Q9. Declare and access object properties using dot notation:
let person = { name: "John", age: 30 };
console.log(person.name);
console.log(person.age);
Output :-
John
30
Q10. for...in loop to iterate through object properties:
<script>
let student = { name: "Alice", age: 20, grade: "A" };
for (let key in student) {
document.write(key + ": " + student[key] + "<br>");
}
</script>
Output :-
name: Alice
age: 20
grade: A
6 Marks Questions
Q1. Write a JavaScript program to input a number and check whether it is prime using loops.
<!DOCTYPE html>
<html>
<body>
<script>
let num = parseInt(prompt("Enter a number:"));
let isPrime = true;
if (num <= 1) {
isPrime = false;
} else {
for (let i = 2; i <= Math.sqrt(num); i++) {
if (num % i === 0) {
isPrime = false;
break;
}
}
}
document.write(isPrime ? "Prime" : "Not Prime");
</script>
</body>
</html>
Output :- Prime
Q2. Factorial using for, while, and do...while:
<script>
// For loop
let n = 5, fact = 1;
for(let i=1; i<=n; i++) fact *= i;
document.write("Factorial (for): " + fact + "<br>");
// While loop
fact = 1; let i = 1;
while(i <= n) { fact *= i; i++; }
document.write("Factorial (while): " + fact + "<br>");
// Do...while loop
fact = 1; i = 1;
do { fact *= i; i++; } while(i <= n);
document.write("Factorial (do...while): " + fact);
</script>
Output :-
Factorial (for): 120
Factorial (while): 120
Factorial (do...while): 120
Q3. Multiplication table of N (1 to 10):
<script>
let N = 7;
for(let i = 1; i <= 10; i++) {
document.write(N + " x " + i + " = " + (N*i) + "<br>");
}
</script>
Output :-
7 x 1 = 7
7 x 2 = 14
...
7 x 10 = 70
Q4. Arithmetic, relational, and logical operators (theory + example):
Arithmetic: +, -, *, /, %, **
Example: let sum = a + b;
Relational: >, <, >=, <=, ==, !=, ===, !==
Example: if(a > b) {...}
Logical: &&, ||, !
Example: if(a > 0 && b > 0) {...}
let a = 10, b = 5;
console.log(a + b); // arithmetic
console.log(a > b); // relational
console.log(a > 0 && b > 0); // logical
Output :-
15
true
true
Q5. Types of expressions in JavaScript:
1. Arithmetic Expression → x + y
2. String Expression → "Hello" + "World"
3. Logical Expression → a && b
4. Assignment Expression → x = 5
5. Function Expression → let add = function(a,b){return a+b;}
Output :-
Honda Corolla
Q6. car object with getter and setter:
<script>
let car = {
brand: "Toyota",
model: "Corolla",
get fullName() {
return this.brand + " " + this.model;
},
set updateBrand(newBrand) {
this.brand = newBrand;
}
};
car.updateBrand = "Honda";
document.write(car.fullName);
</script>
Output :-
Honda Corolla
Q7. Sum of first 10 natural numbers using a loop:
<script>
let sum = 0;
for(let i = 1; i <= 10; i++) sum += i;
document.write("Sum: " + sum);
</script>
Output :-
Sum: 55
Q8. Factorial using loop (simpler version):
<script>
let n = 5, fact = 1;
for(let i=1; i<=n; i++) fact *= i;
document.write("Factorial: " + fact);
</script>
Output :-
Factorial: 120
