JavaScript Booleans - Learn Booleans in JavaScript
JavaScript Booleans
- A JavaScript Boolean contains two values: true or false.
Boolean Values
In programming, you will frequently require a data type that can only hold one of two values, such as
- YES / NO
- ON / OFF
- TRUE / FALSE
For this, JavaScript has a Boolean data type. It can only take the values true or false.
The Boolean() Function
- You can use the Boolean() function to find out if an expression (or a variable) is true.
Sample Code
<html>
<body>
<h2>JavaScript Booleans</h2>
<p>The value of Boolean(20 > 10):</p>
<p id="bool"></p>
<script>
document.getElementById("bool").innerHTML = Boolean(20 > 10);
</script>
</body>
</html>
Output
JavaScript Booleans
The value of Boolean(20 > 10):
True
Conditions and Comparisons
| Operator | Description | Example |
|---|---|---|
| == | equal to | if (day == "Monday") |
| > | greater than | if (salary > 9000) |
| < | less than | if (age < 18) |
Everything With a "Value" is True
Sample Code
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Booleans</h2>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML =
"300 is " + Boolean(300) + "<br>" +
"4.14 is " + Boolean(4.14) + "<br>" +
"-65 is " + Boolean(-65) + "<br>" +
"Any (not empty) string is " + Boolean("Hello") + "<br>" +
"Even the string 'false' is " + Boolean('false') + "<br>" +
"Any expression (except zero) is " + Boolean(5 + 5 + 4.14);
</script>
</body>
</html>
Output
JavaScript Booleans
300 is true
4.14 is true
-65 is true
Any (not empty) string is true
Even the string 'false' is true
Any expression (except zero) is true
Everything Without a "Value" is False
Sample Code
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Booleans</h2>
<p>Display the Boolean value of 0:</p>
<p id="demo"></p>
<script>
let x = 0;
document.getElementById("demo").innerHTML = Boolean(x);
</script>
</body>
</html>
Output
JavaScript Booleans
Display the Boolean value of 0:
false