如何在Node.js中按name分组比较amounts并筛选JSON数据？

需求描述 #

我有如下JSON格式的数据：

[
  {
    "symbol": "USDC",
    "name": "USD Coin",
    "decimals": "6",
    "id": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "feeTier": "100",
    "amounts": [2499.769116, 2500.269174]
  },
  {
    "symbol": "WETH",
    "name": "Wrapped Ether",
    "decimals": "18",
    "id": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
    "feeTier": "3000",
    "amounts": [1.0526261272920125, 1.0590149439506866]
  },
  {
    "symbol": "USDC",
    "name": "USD Coin",
    "decimals": "6",
    "id": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "feeTier": "500",
    "amounts": [2499.591796, 2502.09356]
  },
  {
    "symbol": "WETH",
    "name": "Wrapped Ether",
    "decimals": "18",
    "id": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
    "feeTier": "500",
    "amounts": [1.0551711392408099, 1.0565026582314214]
  },
  {
    "symbol": "FRAX",
    "name": "Frax",
    "decimals": "18",
    "id": "0x853d955acef822db058eb8505911ed77f175b99e",
    "feeTier": "500",
    "amounts": [2505.1101184400254, 2507.620759133425]
  }
]

需要将具有相同name的对象分组，比较每组内对象amounts数组的第一个元素，保留该元素值更大的对象，最终期望输出结果如下：

[
  {
    "symbol": "USDC",
    "name": "USD Coin",
    "decimals": "6",
    "id": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "feeTier": "100",
    "amounts": [2499.769116, 2500.269174]
  },
  {
    "symbol": "WETH",
    "name": "Wrapped Ether",
    "decimals": "18",
    "id": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
    "feeTier": "3000",
    "amounts": [1.0526261272920125, 1.0590149439506866]
  },
  {
    "symbol": "FRAX",
    "name": "Frax",
    "decimals": "18",
    "id": "0x853d955acef822db058eb8505911ed77f175b99e",
    "feeTier": "500",
    "amounts": [2505.1101184400254, 2507.620759133425]
  }
]

请问如何在Node.js中实现这一需求？

实现方案 #

可以通过Array.prototype.reduce方法完成分组和筛选逻辑，具体步骤如下：

1. 用reduce遍历原始数据，以name为键构建临时对象，存储每个名称对应的最优对象
2. 遍历每个对象时，与临时对象中同名称的对象比较amounts[0]的值，保留数值更大的对象
3. 最后将临时对象的取值转换为数组，得到最终结果

完整代码示例 #

const originalData = [
  {
    "symbol": "USDC",
    "name": "USD Coin",
    "decimals": "6",
    "id": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "feeTier": "100",
    "amounts": [2499.769116, 2500.269174]
  },
  {
    "symbol": "WETH",
    "name": "Wrapped Ether",
    "decimals": "18",
    "id": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
    "feeTier": "3000",
    "amounts": [1.0526261272920125, 1.0590149439506866]
  },
  {
    "symbol": "USDC",
    "name": "USD Coin",
    "decimals": "6",
    "id": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "feeTier": "500",
    "amounts": [2499.591796, 2502.09356]
  },
  {
    "symbol": "WETH",
    "name": "Wrapped Ether",
    "decimals": "18",
    "id": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
    "feeTier": "500",
    "amounts": [1.0551711392408099, 1.0565026582314214]
  },
  {
    "symbol": "FRAX",
    "name": "Frax",
    "decimals": "18",
    "id": "0x853d955acef822db058eb8505911ed77f175b99e",
    "feeTier": "500",
    "amounts": [2505.1101184400254, 2507.620759133425]
  }
];

// 核心处理逻辑
const result = Object.values(originalData.reduce((acc, current) => {
  const currentAmount = current.amounts[0];
  // 若当前名称未存入，或当前对象的amounts[0]更大，则更新存储内容
  if (!acc[current.name] || currentAmount > acc[current.name].amounts[0]) {
    acc[current.name] = current;
  }
  return acc;
}, {}));

// 输出格式化后的结果
console.log(JSON.stringify(result, null, 2));

代码说明 #

• reduce方法的初始值为一个空对象，用来临时存储每个name对应的最优对象
• 每次遍历判断：如果当前name未在临时对象中，或者当前对象的amounts[0]数值更大，就替换临时对象中该name对应的内容
• 最后通过Object.values()将临时对象的所有值提取为数组，得到目标结果

内容的提问来源于stack exchange，提问作者gencero