JavaScript Boolean Reference
See Also:
Complete Boolean reference
Revised July 2025
| Name | Description |
|---|---|
| Boolean() | Returns a boolean |
| new Boolean() | Returns a boolean object |
| constructor | Returns the function that created JavaScript's Boolean prototype |
| prototype | Allows you to add properties and methods to the Boolean prototype |
| toString() | Converts a boolean value to a string, and returns the result |
| valueOf() | Returns the primitive value of a boolean |
Boolean Use Cases
Boolean values are fundamental for logical operations and control flow in JavaScript programming.
Comparisons
All comparison operators (like ==, !=, <, >) return true or false.
Given that x = 5, the table below explains comparison:
| Description | Example | Returns |
|---|---|---|
| Not equal to | (x == 8) | false |
| Unequal to | (x != 8) | true |
| Greater than | (x > 8) | false |
| Less than | (x < 8) | true |
Conditions
Booleans are extensively used in if statements to determine the code blocks to executec.
| Example | Returns |
|---|---|
| if (day == "Monday") | true or false |
| if (salary > 9000) | true or false |
| if (age < 18) | true or false |
Loops
Booleans are extensively used in loops to determine conditions for looping.
| Description | Example |
|---|---|
| For loop | for (i = 0; i < 5; i++) |
| While loop | while (i < 10) |
| For in loop | for (x in person) |
| For of loop | for (x of cars) |
