JavaScript Boolean()
The Boolean() Function
The Boolean() function creates primitive boolean values.
The new Boolean() constructor creates Boolean objects.
Note
Booleans are normally primitive values.
Parameters
| Parameter | Description |
|---|---|
| value | Optional. A value to convert to true or false.Defalt is false. |
Return Value
| Call | Returns |
|---|---|
Boolean(value) |
A primitive boolean |
new Boolean(value) |
A Boolean object |
Boolean() vs new Boolean()
Calling Boolean() converts a value to a primitive boolean.
Calling new Boolean() creates a Boolean object.
Example
let a = Boolean(1);
let b = new Boolean(1);
(typeof a) // boolean
(typeof b) // object
Try it Yourself »
Boolean Conversion
The Boolean() function converts values to true or false.
| Expression | Result |
|---|---|
Boolean(1) |
true |
Boolean(0) |
false |
Boolean("Hello") |
true |
Boolean("") |
false |
Boolean(null) |
false |
Boolean(undefined) |
false |
Boolean(NaN) |
false |
Primitive Booleans
Most JavaScript booleans are primitive values.
Boolean Objects
The new Boolean() constructor creates Boolean objects.
Note
Boolean objects are rarely needed.
Primitive vs Object Comparison
| Primitive - Recommended | Boolean Object - Rarely needed |
|---|---|
let x = true |
let x = new Boolean(true) |
| typeof = boolean | typeof = object |
Important Warning
Boolean objects are always truthy.
Example
let x = new Boolean(false);
if (x) {
document.getElementById("demo").innerHTML = "TRUE";
}
Try it Yourself »
This happens because objects are truthy, even when the contained value is false.
Common Methods
toString()valueOf()
Object Hierarchy
Boolean objects inherit from Object.
Object └─ Boolean
Boolean() Questions
| Question | Answer |
|---|---|
| Constructor Type | Function |
| Creates | Primitive booleans or Boolean objects |
| Inherits From | Object (for Boolean objects) |
| Primitive Type | boolean |
Browser Support
Boolean() is an ECMAScript1 (JavaScript 1997) feature.
It is supported in all browsers:
| Chrome | Edge | Firefox | Safari | Opera |
