Basic input and output operations

In JavaScript, basic input and output operations are essential for interacting with users and debugging. Here's how you can handle basic input and output using the console, alerts, and prompts.

1. Console Output

The console.log() method is used to display output in the browser's console (usually for debugging purposes).

Syntax:

console.log("Hello, World!");

Examples:

let name = "Amit";

console.log("Your name is " + name);  // Output: Your name is Amit

let x = 5;

let y = 10;

console.log("The sum is: ", x + y);   // Output: The sum is: 15

• The console can also be used to display objects, arrays, or any data type.

let person = {firstName: "John", lastName: "Doe", age: 25};

console.log(person);

2. Alerts (Output)

The alert() method displays a pop-up dialog box with a message to the user. This is a simple way to provide output but should be used sparingly as it interrupts user interaction.

Syntax:

alert("This is an alert message!");

Examples:

let message = "Welcome to our website!";

alert(message);  // Displays a pop-up with the message "Welcome to our website!"

3. Prompt (Input)

The prompt() method displays a dialog box asking for user input. It returns the user's input as a string, or null if the user cancels the dialog.

Syntax:

let userInput = prompt("Please enter your name:");

Examples:

let age = prompt("Enter your age:");

console.log("Your age is " + age);  // Output the age entered by the user

You can also use prompt() for simple calculations:

let num1 = prompt("Enter the first number:");

let num2 = prompt("Enter the second number:");

let sum = Number(num1) + Number(num2);

alert("The sum is: " + sum);

4. Confirm (User Confirmation)

The confirm() method displays a dialog box with OK and Cancel buttons. It returns true if the user clicks "OK" and false if the user clicks "Cancel".

Syntax:

let isConfirmed = confirm("Do you want to continue?");

Examples:

let proceed = confirm("Are you sure you want to delete this file?");

if (proceed) {

  console.log("File deleted.");

} else {

  console.log("Action canceled.");

}

Summary:

• console.log(): Outputs information to the browser's console, mainly for debugging purposes.
• alert(): Displays a simple pop-up with a message, but disrupts user flow.
• prompt(): Prompts the user to input some data and returns the input as a string.
• confirm(): Asks the user to confirm an action and returns a boolean (true for OK, false for Cancel).