如何在JavaScript中从对象数组提取指定键值对？

现有如下JavaScript数据：

records = [{id: 231, first_name: "Jack", last_name: "Aston", email: "jack55@xyz.com"}, {id: 232, first_name: "Roy", last_name: "Dillon", email: "roy@xy.com"}, {id: 233, first_name: "Jacy", last_name: "Wilson", email: "jacy@x.com"}]

fields = ['id', 'email', 'last_name']

需要从records数组中仅提取fields指定的字段，得到如下格式的新数组：

new_records = [{id: 231, email: "jack55@xyz.com", last_name: "Aston"}, {id: 232, email: "roy@xy.com", last_name: "Dillon"}, {id: 233, email: "jacy@x.com", last_name: "Wilson"}]

下面是几种可行的实现方式：

方法一：map + reduce 组合 #

遍历数组每个对象，通过reduce筛选指定字段并构建新对象，适合字段数量不固定的场景：

const new_records = records.map(record => {
  return fields.reduce((acc, field) => {
    acc[field] = record[field];
    return acc;
  }, {});
});

方法二：map + 对象解构 #

如果明确知道要提取的字段，用解构赋值写法更简洁直观：

const new_records = records.map(({ id, email, last_name }) => ({ id, email, last_name }));

方法三：封装通用工具函数 #

如果需要多次复用提取逻辑，可以封装成工具函数，传入数据源和目标字段即可：

function extractFields(data, fields) {
  return data.map(item => {
    const result = {};
    fields.forEach(field => {
      if (item.hasOwnProperty(field)) {
        result[field] = item[field];
      }
    });
    return result;
  });
}

// 调用示例
const new_records = extractFields(records, fields);

内容的提问来源于stack exchange，提问作者user12763413