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isBoolean()

isBoolean(value): value is boolean

Checks if a value is a boolean.

Parameters​

value: unknown​

The value to check.

Returns: value is boolean​

true if the value is a boolean, false otherwise.

Since​

1.0.0

Example​

isBoolean(true);  // => true
isBoolean(false); // => true
isBoolean(1);     // => false
isBoolean('true'); // => false

How it works?​

Type guard that checks if a value is a boolean.

Type Narrowing​

Common Checks​

ValueResult
true true
false true
Boolean(1) true
new Boolean(true) false (boxed)
1 false
'true' false

Use Cases​

Check binary flags 📌​

Verify if a value is strictly true or false. Perfect for validating configuration flags or toggle states.

if (isBoolean(config.isEnabled)) {
  toggleFeature(config.isEnabled);
}