js通过属性获取对象属性

const person = {
  name: 'Alice',
  age: 25
};

console.log(person.name); // 输出: Alice
console.log(person.age);  // 输出: 25

const person = {
  name: 'Alice',
  age: 25
};

const propertyName = 'name';
console.log(person[propertyName]); // 输出: Alice

console.log(person['age']); // 输出: 25

const person = {
  name: 'Alice',
  age: 25
};

const keys = Object.keys(person);
console.log(keys); // 输出: ['name', 'age']

const person = {
  name: 'Alice',
  age: 25
};

Object.defineProperty(person, 'secret', {
  value: 'I love JavaScript',
  enumerable: false
});

const allKeys = Object.getOwnPropertyNames(person);
console.log(allKeys); // 输出: ['name', 'age', 'secret']

const person = {
  name: 'Alice',
  age: 25
};

if ('name' in person) {
  console.log('Name exists');
}

if (person.hasOwnProperty('age')) {
  console.log('Age exists');
}

const person = {
  'first-name': 'Alice',
  'last name': 'Smith'
};

console.log(person['first-name']); // 输出: Alice
console.log(person['last name']); // 输出: Smith

const person = {
  name: 'Alice'
};

console.log(person.age); // 输出: undefined

if ('age' in person) {
  console.log(person.age);
} else {
  console.log('Age does not exist');
}