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JavaScript Program to Convert Kilometers to Miles

Converting kilometers to miles is a straightforward mathematical task often needed in applications involving distance calculations. In JavaScript, you can easily perform this conversion using a predefined conversion factor. The formula to convert kilometers to miles is:

Miles = Kilometers × 0.621371

In this guide, we will explore different ways to create a JavaScript program to convert kilometers to miles, complete with examples, explanations, and outputs.

JavaScript Program to Convert Kilometers to Miles Using Hardcoded Values

The simplest approach is to use predefined values for the kilometers.

Code

// JavaScript program to convert kilometers to miles
let kilometers = 10;
let miles = kilometers * 0.621371;
console.log(`${kilometers} kilometers is equal to ${miles} miles.`);

Output

10 kilometers is equal to 6.21371 miles.

Explanation

  • The variable kilometers holds the distance in kilometers.

  • The conversion factor 0.621371 is used to calculate the equivalent distance in miles.

  • The result is displayed using console.log().

JavaScript Program to Convert Kilometers to Miles Using User Input

This method allows the user to input the value in kilometers interactively.

Code

// Convert kilometers to miles in JavaScript using user input
let kilometers = parseFloat(prompt("Enter the distance in kilometers:"));
let miles = kilometers * 0.621371;
alert(`${kilometers} kilometers is equal to ${miles} miles.`);

Output

The program prompts the user to input a value and displays the result in an alert box.

Explanation

  • The prompt() function takes user input for kilometers.

  • The conversion factor is applied to compute the distance in miles.

  • The result is displayed using an alert box.

JavaScript Program to Convert Kilometers to Miles Using a Function for Reusability

To make the program modular, you can encapsulate the conversion logic in a function.

Code

// JavaScript program to convert kilometers to miles using a function
function convertKilometersToMiles(kilometers) {
    return kilometers * 0.621371;
}

let kilometers = 15;
let miles = convertKilometersToMiles(kilometers);
console.log(`${kilometers} kilometers is equal to ${miles} miles.`);

Output

15 kilometers is equal to 9.320565 miles.

Explanation

  • The convertKilometersToMiles function takes kilometers as input and returns the equivalent distance in miles.

  • The function makes the code reusable for different inputs.

JavaScript Program to Convert Kilometers to Miles Using a Class

You can create a class to encapsulate the logic for converting kilometers to miles.

Code

// JavaScript program to convert kilometers to miles using a class
class DistanceConverter {
    static convertKilometersToMiles(kilometers) {
        return kilometers * 0.621371;
    }
}

let kilometers = 20;
let miles = DistanceConverter.convertKilometersToMiles(kilometers);
console.log(`${kilometers} kilometers is equal to ${miles} miles.`);

Output

20 kilometers is equal to 12.42742 miles.

Explanation

  • The DistanceConverter class contains a static method convertKilometersToMiles for the conversion logic.

  • The static method allows the conversion to be used without creating an instance of the class.

JavaScript Program to Convert Kilometers to Miles Using HTML for Interactive Input

Here’s how to create an interactive program using an HTML form.

Code

<!DOCTYPE html>
<html>
<body>
    <h3>Convert Kilometers to Miles</h3>
    <form>
        <label for="kilometers">Kilometers:</label>
        <input type="text" id="kilometers">
        <button type="button" onclick="convertKilometersToMiles()">Convert</button>
    </form>
    <p id="result"></p>

    <script>
        function convertKilometersToMiles() {
            let kilometers = parseFloat(document.getElementById("kilometers").value);
            let miles = kilometers * 0.621371;
            document.getElementById("result").innerText = `${kilometers} kilometers is equal to ${miles} miles.`;
        }
    </script>
</body>
</html>

Output

The result is shown on the webpage after clicking the "Convert" button.

Explanation

  • The convertKilometersToMiles function retrieves the input value from the HTML form and computes the miles.

  • The result is displayed dynamically on the webpage.