how to check the boolean value in javascript code example

Example 1: js is boolean

if (typeof variable === "boolean"){
  // variable is a boolean
}

Example 2: javascript function return boolean

function  func(){
  return true;
}

isBool = func();
console.log(typeof (isBool));   // output - string


let isBool = func();
console.log(typeof (isBool));   // output - boolean