Web Design& development programming Studio: JavaScript if....Else

Wednesday, June 21, 2023

JavaScript if, else, and else if

Conditional Statements

Very often when you write code, you want to perform different actions for different decisions.

You can use conditional statements in your code to do this.

In JavaScript we have the following conditional statements:

Use if to specify a block of code to be executed, if a specified condition is true
Use else to specify a block of code to be executed, if the same condition is false
Use else if to specify a new condition to test, if the first condition is false
Use switch to specify many alternative blocks of code to be executed
The if Statement
Use the if statement to specify a block of JavaScript code to be executed if a condition is true.
Example
<html>
<body>

<h2>JavaScript if</h2>

<p>Display "Good day!" if the hour is less than 18:00:</p>

<p id="demo">Good Evening!</p>

<script>
if (new Date().getHours() < 18) {
document.getElementById("demo").innerHTML = "Good day!";
}
</script>

</body>
</html>
The else Statement
Use the else statement to specify a block of code to be executed if the condition is false.
Example
<!DOCTYPE html>
<html>
<body>

<h2>JavaScript if .. else</h2>

<p>A time-based greeting:</p>

<p id="demo"></p>

<script>
const hour = new Date().getHours();
let greeting;

if (hour < 18) {
greeting = "Good day";
} else {
greeting = "Good evening";
}

document.getElementById("demo").innerHTML = greeting;
</script>

</body>
</html>