The Boolean object in JavaScript is a global object and constructor function that represents boolean values: true or false. Here’s an overview of the Boolean object:
1. Creating Boolean Objects:
- You can create a
Booleanobject using theBoolean()constructor:
const boolObj = new Boolean(true);
However, it’s more common to use primitive boolean literals:
const bool = true;
2. Properties of Boolean Object:
Boolean.prototype: Represents the prototype for theBooleanconstructor.
3. Methods of Boolean Object:
Since boolean primitives do not have methods, the Boolean object has only one method:
.toString(): Returns a string representing the specified Boolean object.
const boolObj = new Boolean(true);
console.log(boolObj.toString());
// Outputs: "true"
However, it’s important to note that using the Boolean constructor to create boolean objects is generally not recommended in most cases. Instead, you should use primitive boolean literals (true and false) directly, as they are more efficient and sufficient for most use cases:
const bool = true;
Converting Values to Booleans:
JavaScript provides several ways to convert values to booleans:
- Boolean Conversion: Any value can be converted to a boolean using the
Boolean()function.
console.log(Boolean(0));
// Outputs: false
console.log(Boolean(""));
// Outputs: false
console.log(Boolean(42));
// Outputs: true
console.log(Boolean("Hello"));
// Outputs: true
- Truthy and Falsy Values: In JavaScript, some values are considered “truthy” (evaluate to
true) and others are considered “falsy” (evaluate tofalse).
console.log(Boolean(undefined));
// Outputs: false
console.log(Boolean(null));
// Outputs: false
console.log(Boolean(0));
// Outputs: false
console.log(Boolean(""));
// Outputs: false
console.log(Boolean(NaN));
// Outputs: false
console.log(Boolean("Hello"));
// Outputs: true
console.log(Boolean(42));
// Outputs: true
console.log(Boolean([]));
// Outputs: true
Comparisons and Conditions
- The chapter JS Comparisons gives a full overview of comparison operators.
- The chapter JS If Else gives a full overview of conditional statements.
| Operator | Description | Example |
|---|---|---|
| == | equal to | if (day == "Monday") |
| > | greater than | if (salary > 9000) |
| < | less than | if (age < 18) |
