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.
Table of Content
- Using Switch Statement
- Using if-else Statements
- Using Ternary Operator
- Using Math.abs()
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
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
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.
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:
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.
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:
Using Math.abs()
In this approach, we utilize the Math.abs() method to determine if a number is positive, negative, or zero. The Math.abs() method returns the absolute value of a number, which is its magnitude without regard to its sign. We can then compare the result with the original number to determine its sign.
Example: We will check if a number is positive, negative, or zero using the Math.abs() method.
function checkNumberSign(number) {
if (isNaN(number)) {
console.log("Invalid input. Please enter a valid number.");
} else {
if (number === 0) {
console.log("The number is zero.");
} else if (number === Math.abs(number)) {
console.log("The number is positive.");
} else {
console.log("The number is negative.");
}
}
}
// Test cases
checkNumberSign(5); // Output: The number is positive.
checkNumberSign(-7); // Output: The number is negative.
checkNumberSign(0); // Output: The number is zero.
Output
The number is positive. The number is negative. The number is zero.