将嵌套对象转换为FormData

function convertNestedObjectToFormData(obj, formData, parentKey) {
  for (let key in obj) {
    if (obj.hasOwnProperty(key)) {
      let propName = parentKey ? `${parentKey}[${key}]` : key;
      let propValue = obj[key];

      if (typeof propValue === 'object' && !(propValue instanceof File)) {
        convertNestedObjectToFormData(propValue, formData, propName);
      } else if (propValue instanceof File) {
        formData.append(propName, propValue);
      } else {
        formData.append(propName, propValue);
      }
    }
  }
}

// 示例嵌套对象
let nestedObject = {
  name: 'John Doe',
  age: 30,
  address: {
    street: '123 Main St',
    city: 'New York',
    state: 'NY'
  },
  avatar: new File(['avatar.jpg'], 'avatar.jpg')
};

// 创建一个空的FormData对象
let formData = new FormData();

// 转换嵌套对象为FormData
convertNestedObjectToFormData(nestedObject, formData);

// 现在可以将formData对象用于网络请求发送到服务器