&&= (逻辑与赋值运算符) (x &&= y) //只在x为真时赋值 let x = 0; let y = 1; x &&= 0; // 0 x &&= 1; // 0 y &&= 1; // 1 y &&= 0; // 0 ||= (逻辑或赋值运算符) (x ||= y) //只在x为假时赋值 const a = { duration: 50, title: '' }; a.duration ||= 10; console.log(a.duration); // expected out...