如何基于CategoryDesc与SubCatDesc两个属性获取数组去重值？

针对你需要按CategoryDesc和SubCatDesc两个属性组合去重的需求，这里提供几种简洁实用的实现方式：

方法1：Set结合JSON.stringify序列化 #

这种方式利用Set自动去重的特性，先将每个对象序列化为字符串，去重后再转回对象：

const array = [
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc": "FRD" ,"SubCatDesc":"VRD"},
  { "CategoryDesc": "FRD" ,"SubCatDesc":"VRD"},
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc":"FRD", "SubCatDesc":"BBC"}
];

const uniqueArray = Array.from(new Set(array.map(item => JSON.stringify(item)))).map(str => JSON.parse(str));
console.log(uniqueArray);

说明：如果数组中对象的属性顺序完全一致，这个方法可以直接用；如果属性顺序可能不同，建议用下面的方法。

方法2：reduce+对象映射（推荐） #

通过自定义唯一键（两个属性拼接），用reduce遍历数组并存储唯一的对象，效率更高：

const array = [
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc": "FRD" ,"SubCatDesc":"VRD"},
  { "CategoryDesc": "FRD" ,"SubCatDesc":"VRD"},
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc":"FRD", "SubCatDesc":"BBC"}
];

const uniqueMap = array.reduce((acc, current) => {
  // 用两个属性拼接成唯一标识键，选不会出现在属性值里的符号当分隔符
  const key = `${current.CategoryDesc}|${current.SubCatDesc}`;
  // 键不存在时才存入对象
  if (!acc[key]) acc[key] = current;
  return acc;
}, {});

// 提取对象中的值组成去重后的数组
const uniqueArray = Object.values(uniqueMap);
console.log(uniqueArray);

方法3：ES6 Map结构实现 #

和方法2逻辑类似，用Map存储唯一键值对，语义更清晰：

const array = [
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc": "FRD" ,"SubCatDesc":"VRD"},
  { "CategoryDesc": "FRD" ,"SubCatDesc":"VRD"},
  { "CategoryDesc":"SEC Violations (Insider Trading, Securities Fraud)", "SubCatDesc":"BBC"},
  { "CategoryDesc":"FRD", "SubCatDesc":"BBC"}
];

const uniqueMap = new Map();
array.forEach(item => {
  const key = `${item.CategoryDesc}|${item.SubCatDesc}`;
  if (!uniqueMap.has(key)) {
    uniqueMap.set(key, item);
  }
});

const uniqueArray = Array.from(uniqueMap.values());
console.log(uniqueArray);

以上三种方法都能得到你预期的去重结果，其中方法2和3在性能和兼容性上表现更优，推荐使用。

内容的提问来源于stack exchange，提问作者Jack