JavaScript Program to Check if a number is Positive, Negative, or Zero

In this article, we are going to learn if a number is positive, negative, or zero, for numerous mathematical operations and conditional statements in JavaScript. It is critical to know if a given number is positive, negative, or zero. This article provides a straightforward approach in JavaScript that lets you determine whether a given number belongs to one of these groups.

Several methods can be used to Check if a number is Positive, Negative, or Zero.

We will explore all the above methods along with their basic implementation with the help of examples.

Approach 1: Using Switch Statement

In this approach, we are using a switch statement to check a number’s sign (positive, negative, or zero) based on Math.sign() method, this method is used to know the sign of a number, indicating whether the number specified is negative or positive.

Syntax:

switch (expression) {
    case value1:
        statement1;
        break;
    case value2:
        statement2;
        break;
    . . .
    case valueN:
        statementN;
        break;
    default:
        statementDefault;
}

Example: In this example, we are using the above-explained approach

Javascript

function numberChecking(num) {
    switch (Math.sign(num)) {
        case 1:
            console.log("The number is Positive");
            break;
        case -1:
            console.log("The number is Negative");
            break;
        default:
            console.log("The number is Zero");
    }
}

numberChecking(12);
// Output: Positive
numberChecking(-1);
// Output: Negative
numberChecking(0);
// Output: Zero

Output

The number is Positive
The number is Negative
The number is Zero

Approach 2: Using if-else Statements

In this approach we are using the if-else or conditional statement will perform some action for a specific condition. If the condition meets then a particular block of action will be executed otherwise it will execute another block of action that satisfies that particular condition.

Syntax:

if (condition) {
    // Executes this block if
    // condition is true
}
else {
    // Executes this block if
    // condition is false
}

Example: In this example, we are using the above-explained approach.

Javascript

const number = prompt("Enter a number");
if (number > 0) {
    console.log("The number is positive");
}
else if (number < 0) {
    console.log("The number is negative");
}
else {
    console.log("The number is zero");
};

Output:

Approach 3: Using Ternary Operator

The ternary operator in JavaScript is an efficient one-line conditional statement that evaluates an expression and returns one of two defined values depending on a specific condition.

Syntax:

condition ? value if true : value if false

Example: In this example, we are using the above-explained approach.

Javascript

function checkNumberSign() {
  const input = prompt("Enter a number:");
  const number = Number(input);

  if (isNaN(number)) {
    console.log("Invalid input. Please enter a valid number.");
  } else {
    const result =
      number === 0 ? "The number is zero." :
      number > 0 ? `${number} is positive.` : `${number} is negative.`;

    console.log(result);
  }
}

// Call the function to start the program
checkNumberSign();

Output: