if, else, else if - Blackbox Learning Docs

if Statement

Use if to specify a code block to be executed, if a specified condition is true.

Syntax

if (condition) {

// code to execute if the condition is true

}

<!DOCTYPE html>
<html>
<body>

<h2>If Statement</h2>

<script>
let age = 20;

if (age >= 18) {
  document.write("You can vote");
}
</script>

</body>
</html>

else Statement

Use else to specify a code block to be executed, if the same condition is false.

Syntax

if (condition) {

// code to execute if the condition is true

} else {

// code to execute if the condition is false

}

<!DOCTYPE html>
<html>
<body>

<h2>If Else Statement</h2>

<script>
let age = 16;

if (age >= 18) {
  document.write("You can vote");
} else {
  document.write("You cannot vote");
}
</script>

</body>
</html>

else if Statement

Use else if to specify a new condition to test, if the first condition is false.

Syntax

if (condition1) {

// code to execute if condition1 is true

} else if (condition2) {

// code to execute if the condition1 is false and condition2 is true

} else {

// code to execute if the condition1 is false and condition2 is false

}

<!DOCTYPE html>
<html>
<body>

<h2>Else If Statement</h2>

<script>
let marks = 75;

if (marks >= 90) {
  document.write("Grade A");
} else if (marks >= 70) {
  document.write("Grade B");
} else {
  document.write("Grade C");
}
</script>

</body>
</html>