Conditional statements allow you to write code that makes decisions based on certain conditions.
They are
if, if-else, else-if
Example 1
var element = document.getElementById("my-element");
if (element.classList.contains("active")) {
element.classList.remove("active");
element.classList.add("inactive");
} else {
element.classList.remove("inactive");
element.classList.add("active");
}
Example 2
<!DOCTYPE html>
<html>
<head>
<title>Conditional Statements Example</title>
</head>
<body>
<h1>Grade Calculator</h1>
<p>Enter your score below:</p>
<input type="text" id="score">
<button onclick="calculateGrade()">Calculate</button>
<p id="result"></p>
<script>
function calculateGrade() {
// Get the score entered by the user
var score = document.getElementById("score").value;
// Check if the score is valid
if (score < 0 || score > 100) {
document.getElementById("result").innerHTML = "Please enter a valid score between 0 and 100";
return;
}
// Calculate the grade based on the score
var grade;
if (score >= 90) {
grade = "A";
} else if (score >= 80) {
grade = "B";
} else if (score >= 70) {
grade = "C";
} else if (score >= 60) {
grade = "D";
} else {
grade = "F";
}
// Display the grade to the user
document.getElementById("result").innerHTML = "Your grade is: " + grade;
}
</script>
</body>
</html>