如何让对象输出默认值

const obj = {
  name: 'John',
  age: null,
};

console.log(obj.name || 'Default Name'); // Output: John
console.log(obj.age || 25); // Output: 25 (default value)

const obj = {
  name: 'John',
  age: undefined,
};

console.log(obj.name !== undefined ? obj.name : 'Default Name'); // Output: John
console.log(obj.age !== undefined ? obj.age : 25); // Output: 25 (default value)

const obj = {
  name: 'John',
  age: undefined,
};

const { name = 'Default Name', age = 25 } = obj;

console.log(name); // Output: John
console.log(age); // Output: 25 (default value)