Check Even or Odd

Program to check if a number is even or odd

BeginnerTopic: Conditional Programs

JavaScript Check Even or Odd Program

This program helps you to learn the fundamental structure and syntax of JavaScript programming.

// Method 1: Using if-else
let number = 7;

if (number % 2 === 0) {
    console.log(number + " is even");
} else {
    console.log(number + " is odd");
}

// Method 2: Using ternary operator
let num = 8;
let result = (num % 2 === 0) ? "even" : "odd";
console.log(num + " is " + result);

// Method 3: Using function
function checkEvenOdd(n) {
    if (n % 2 === 0) {
        return "even";
    } else {
        return "odd";
    }
}

console.log("10 is " + checkEvenOdd(10));
console.log("15 is " + checkEvenOdd(15));

Output

7 is odd
8 is even
10 is even
15 is odd

Understanding Check Even or Odd

This program demonstrates conditional logic using the modulus operator.

Modulus Operator (%)

The modulus operator returns the remainder after division:

•number % 2 === 0 → Even number

•number % 2 === 1 → Odd number

If-Else Statement

Basic conditional structure:

if (condition) {
} else {

    // code if false
}

    // code if true

Ternary Operator

Shorthand for if-else:

condition ? valueIfTrue : valueIfFalse

Comparison Operators

•===: Strict equality (checks value and type)

•!==: Strict inequality

•==: Loose equality (avoid, can cause bugs)

•!=: Loose inequality (avoid)

Best Practice:

Always use === for equality checks!

Function Approach

Creating reusable function:

function checkEvenOdd(n) {
}

    return (n % 2 === 0) ? "even" : "odd";

Edge Cases

checkEvenOdd(0);   // "even"
checkEvenOdd(-2);  // "even"
checkEvenOdd(-3);  // "odd"

Let us now understand every line and the components of the above program.

Note: To write and run JavaScript programs, you need to set up the local environment on your computer. Refer to the complete article Setting up JavaScript Development Environment. If you do not want to set up the local environment on your computer, you can also use online IDE to write and run your JavaScript programs.

Practical Learning Notes for Check Even or Odd

This JavaScript program is part of the "Conditional Programs" topic and is designed to help you build real problem-solving confidence, not just memorize syntax. Start by understanding the goal of the program in plain language, then trace the logic line by line with a custom input of your own. Once you can predict the output before running the code, your understanding becomes much stronger.

A reliable practice pattern is to run the original version first, then modify only one condition or variable at a time. Observe how that single change affects control flow and output. This deliberate style helps you understand loops, conditions, and data movement much faster than copying full solutions repeatedly.

For interview preparation, explain this solution in three layers: the high-level approach, the step-by-step execution, and the time-space tradeoff. If you can teach these three layers clearly, you are ready to solve close variations of this problem under time pressure.

Largest Among Three Numbers