JavaScript Booleans

Boolean Values

Very often, in programming, you will need a data type that can only have one of two values, like

• 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:

Boolean(10 > 9)        // returns true

(10 > 9)              // also returns true10 > 9                // also returns true

Everything With a "Value" is True

Example :

100

3.14

-15

"Hello"

"false"

7 + 1 + 3.14

Everything Without a "Value" is False

var x = 0;
Boolean(x);       // returns false

Booleans Can be Objects

Normally JavaScript booleans are primitive values created from literals:

var x = false;

But booleans can also be defined as objects with the keyword new:

var y = new Boolean(false);

Example :

var x = false;
var y = new Boolean(false);

// typeof x returns boolean// typeof y returns object