The toString() method of Boolean values returns a string representing the specified boolean value.
Syntax
toString()
Parameters
None.
Return value
A string representing the specified boolean value.
Description
The Boolean object overrides the toString method of Object; it does not inherit
Object.prototype.toString. For Boolean values, the toString method returns a string representation of the boolean value, which is either "true" or "false".
The toString() method requires its this value to be a Boolean primitive or wrapper object. It throws a TypeError for other this values without attempting to coerce them to boolean values.
Because Boolean doesn't have a [@@toPrimitive]() method, JavaScript calls the toString() method automatically when a Boolean object is used in a context expecting a string, such as in a template literal. However, boolean primitive values do not consult the toString() method to be coerced to strings — rather, they are directly converted using the same algorithm as the initial toString() implementation.
Boolean.prototype.toString = () => "Overridden";
console.log(`${true}`); // "true"
console.log(`${new Boolean(true)}`); // "Overridden"
Examples
Using toString()
const flag = new Boolean(true);
console.log(flag.toString()); // "true"
console.log(false.toString()); // "false"