一、以Boolean為對象的兩個方法：

• Boolean.prototype.toString()
  「字串內容」取決於Boolean是true還是false，這個方法會覆蓋Object.prototype.toString()

• Boolean.prototype.valueOf()
  Boolean.prototype.valueOf()返回布林物件的原始型別，覆蓋Object.prototype.valueOf()

二、方法一 Boolean.prototype.toString()
對Boolean使用 toString() 會還傳一個表達布林值字串：

const flag1 = new Boolean(true);

console.log(flag1.toString());       // Expected output: "true"

const flag2 = new Boolean(1);

console.log(flag2.toString());       // Expected output: "true"

創建原本是false的布林物件：

const bNoParam = new Boolean();             //Boolean {false}
const bZero = new Boolean(0);               //Boolean {false}
const bNull = new Boolean(null);            //Boolean {false}
const bEmptyString = new Boolean("");       //Boolean {false}
const bfalse = new Boolean(false);          //Boolean {false}

創建原本是true的布林物件：

const btrue = new Boolean(true);              //Boolean {true}
const btrueString = new Boolean("true");      //Boolean {true}
const bfalseString = new Boolean("false");    //Boolean {true}
const bSuLin = new Boolean("Su Lin");         //Boolean {true}
const bArrayProto = new Boolean([]);          //Boolean {true}  
                                              
const bObjProto = new Boolean({});            //Boolean {true}
//空物件和陣列都是true

Reference
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean/toString