JavaScript-邏輯運算子(Logical operators)

console.log( 0 && 1);//0
console.log( 1 && 0);//0
console.log( 0 || 1);//1
console.log( 1 || 0);//1
console.log(![]);//false
console.log( !1 );//false

函式預設值(Default value)

let product = 20000;
function store(money){
  money = parseInt(money);//預防傳入的是字串類型的數字
  money = (money || money === 0)?money : 20000;//三元運算子
  console.log('購買後剩餘' + (product-money) + '元');
}
store(2000);//購買後剩餘18000元

參考文獻:
JavaScript 核心篇 (opens new window)

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