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JavaScript if…else example programs

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JavaScript if else statement is a conditional statement that allows you to execute different blocks of code depending on whether a certain condition is true or false. In this tutorial, we will do if…else example programs using JS.

For example flow:

  • You start with the keyword if, followed by a condition that you want to check.
  • If the condition is true, the block of code inside the curly braces {} after the if statement will be executed.
  • If the condition is false, the program will skip the if block and move on to the else block.
  • The else block starts with the keyword else, followed by the block of code inside curly braces {} that should be executed if the condition is false.

JavaScript if…else example programs example

Simple example code of JavaScript programs that use the if…else statement.

1. Checking if a number is positive or negative

<!DOCTYPE html>
<html>
<body>
<script>
    let num = -5;

    if (num >= 0) {
        console.log("The number is positive");
    } else {
        console.log("The number is negative");
    }

</script>
</body>
</html>

Output:

JavaScript if...else example programs

2: Checking if a password is valid

let password = "mypassword123";

if (password.length >= 8 && password.includes("$")) {
  console.log("The password is valid");
} else {
  console.log("The password is invalid");
}

3. Checking if a number is even or odd

let num = 7;

if (num % 2 === 0) {
  console.log("The number is even");
} else {
  console.log("The number is odd");
}

4. Checking the highest number

let num1 = 10;
let num2 = 5;

if (num1 > num2) {
  console.log(num1 + " is the highest number");
} else {
  console.log(num2 + " is the highest number");
}

5. Checking if a year is a leap year

let year = 2024;

if (year % 4 === 0) {
  if (year % 100 === 0) {
    if (year % 400 === 0) {
      console.log(year + " is a leap year");
    } else {
      console.log(year + " is not a leap year");
    }
  } else {
    console.log(year + " is a leap year");
  }
} else {
  console.log(year + " is not a leap year");
}

6. Checking if a string is a palindrome

let str = "racecar";
let reversedStr = str.split("").reverse().join("");

if (str === reversedStr) {
  console.log(str + " is a palindrome");
} else {
  console.log(str + " is not a palindrome");
}

Do comment if you have any doubts or suggestions on this Js if else practice code.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version

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