BoolUnit is a type of Unit that only accepts boolean data type as its value. It ensures that at any point of time the value would always be boolean.

It implements non-deprecated Object.prototype methods like toString and redirects them to the stored boolean value inside the Unit, so when you call BoolUnit.toString() , it'll be executed on the Unit's value instead of the BoolUnit instance itself. Similarly, when you call other Object.prototype methods they are called on the stored value instead of BoolUnit instance.

See API reference for more details.

BoolUnit vs boolean

BoolUnit can not be used as a drop-in replacement for primitive boolean value, since BoolUnit is a non-primitive data structure, and the actual boolean value is stored inside the Unit. See the below comparisons for more clarity.

// initialization
let bool = false; // a variable with prmitive boolean value
const unit = new BoolUnit({initialValue: false});
// initialValue is optional, BoolUnit has false as default value

bool === unit // false
bool === unit.value() // true

unit + '' // 'false'
unit + 1 // 1, because false is converted to 0
unit + 1 // 2, because true is converted to 1

typeof bool === 'boolean' // true
typeof unit === 'object' // true
typeof unit.value() === 'boolean' // true

// value assignment
bool = true;

// value access
console.log(bool) // logs true
console.log(unit.value()) // logs true
// or
unit.subscribe(value => console.log(value)) // logs true, will log future values

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