如何获取对象的所有属性，包括每个子对象的属性？

function getAllProperties(obj) {
  var properties = [];
  
  for (var prop in obj) {
    if (obj.hasOwnProperty(prop)) {
      properties.push(prop);
      
      if (typeof obj[prop] === 'object') {
        var childProperties = getAllProperties(obj[prop]);
        properties = properties.concat(childProperties.map(function(childProp) {
          return prop + '.' + childProp;
        }));
      }
    }
  }
  
  return properties;
}

// 示例对象
var exampleObj = {
  name: 'John',
  age: 30,
  address: {
    street: '123 Main St',
    city: 'New York',
    country: 'USA'
  }
};

// 获取所有属性
var allProperties = getAllProperties(exampleObj);
console.log(allProperties);

[
  "name",
  "age",
  "address",
  "address.street",
  "address.city",
  "address.country"
]