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

In this article, we will discuss how we can determine whether the given number is Positive, Negative, or Zero. As we know if the number is less than 0 then it will be called a “Negative” number if it is greater than 0 then it will be called a “Positive” number. And if it doesn’t lie between them, then it will be 0.

Example:

Input: 10   
Output: Positive number
Input: -12 
Output: Negative number
Input: 0
Output: Zero

These are the following ways by which we can find out whether the number is Positive, Negative, or Zero:

Method 1: Using if-else statement

In this approach, we are using an if-else statement. in which whatever the condition will get satisfied and return true that code block will get executed and it will print the result in the console.

Example: It describes how we can find the given number is Positive, Negative, or Zero using an if-else statement

// Function for number checking 
function NumberSignChecker(n) {
    if (n > 0) {
        console.log("Positive number");
    } else if (n < 0) {
        console.log("Negative number");
    } else {
        console.log("Zero");
    }
}

// Variables holding values
let number1 = -5;
let number2 = 5;
let number3 = 0;

NumberSignChecker(number1); // Negative number
NumberSignChecker(number2); // Positive number
NumberSignChecker(number3); // Zero

Negative number
Positive number
Zero

Time complexity: The time complexity of the above code is O(1), as it takes only one step to complete the operation.

Space complexity: The space complexity of the above code is O(1), as no extra space is required in order to complete the operation.

Method 2: Using ternary operator

In this approach we are using ternary operator. Ternary operator is shorthand of “if-else” statement. If “n<0” is true then it will print “Negative” else it will check for another condition and it will print result accordingly.

Example: It describes how we can find the given number is Positive, Negative, or Zero using ternary operator

let n = 0;

// Using ternary operator
// for solving the
// problem
let ans = n < 0 ? "Negative" : n > 0 ? "Positive" : "Zero";

// Printing result in 
// console
console.log(ans);

Zero

Time complexity: O(1) as it is doing constant operations

Space complexity: O(1) as it is using constant space for variables

Method 3: Using switch case

In this method we are using switch case for solving this problem. Switch statement will check the condition and return the result. If any of case is equivalent to that result then that code block will get executed and it will print result in the console else default statement will get executed automatically.

Example: It describes how we can find the given number is Positive, Negative, or Zero using switch case

// JavaScript program for checking if number
// is positive, negative or zero

let num = 10;

// Switch-case statement
switch (num / num) {
    case 1:
        console.log("Positive nunber");
        break;
    case -1:
        console.log("Negative number");
        break;
    case 0:
        console.log("Zero");
        break;
}

Positive nunber

Time complexity: O(1), as it is doing constant operations

Space complexity: O(1), as it is using constant space for variables

Using Math.sign()

In this approach we are using the Math.sign() method which returns the sign of a number as -1 for negative numbers, 0 for zero, and 1 for positive numbers. It checks the result of Math.sign(num) to determine the sign of the given number and returns the corresponding string.

Example: It describes how we can find the given number is Positive, Negative, or Zero using Math.sign() method.

function checkNumber(num) {
    return Math.sign(num) === 1 ? "Positive" : Math.sign(num
    ) === -1 ? "Negative" : "Zero";
}

console.log(checkNumber(10));
console.log(checkNumber(-5));
console.log(checkNumber(0));

Positive
Negative
Zero

Time complexity: O(1), as it is doing constant operations

Space complexity: O(1), as it is using constant space for variables

Method 5: Using bitwise operators

In this approach, we leverage bitwise operators to check the sign of the integer. Specifically, we use the right shift operator (>>) to extract the sign bit and compare it with 0 to determine whether the number is positive, negative, or zero.

Example:

function checkNumber(num) {
    if (num === 0) {
        return "Zero";
    } else if (num >> 31 !== 0) {
        return "Negative number";
    } else {
        return "Positive number";
    }
}

// Test cases
console.log(checkNumber(10));
console.log(checkNumber(-5));  
console.log(checkNumber(0)); 

Positive number
Negative number
Zero