JavaScript统计数组对象中来源与告警组合的出现频次

嘿，这个需求很常见！我们可以用JavaScript的reduce方法来快速实现，它能帮我们遍历数组的同时，一步步构建出带frequency字段的结构化结果。

先把你的原始数组放出来方便参考：

var array = [ 
  {name: "Source_one", alertName: "Alert_1"}, 
  {name: "Source_three", alertName: "Alert_2"}, 
  {name: "Source_one", alertName: "Alert_3"}, 
  {name: "Source_two", alertName: "Alert_3"}, 
  {name: "Source_one", alertName: "Alert_3"}, 
  {name: "Source_one", alertName: "Alert_3"}, 
  {name: "Source_two", alertName: "Alert_1"}, 
  {name: "Source_one", alertName: "Alert_1"}, 
  {name: "Source_two", alertName: "Alert_1"}, 
  {name: "Source_two", alertName: "Alert_2"}, 
  {name: "Source_one", alertName: "Alert_1"}, 
  {name: "Source_two", alertName: "Alert_2"}, 
  {name: "Source_three", alertName: "Alert_3"}, 
  {name: "Source_two", alertName: "Alert_2"}, 
  {name: "Source_two", alertName: "Alert_3"}, 
  {name: "Source_three", alertName: "Alert_1"}, 
  {name: "Source_three", alertName: "Alert_1"}, 
  {name: "Source_one", alertName: "Alert_3"}, 
  {name: "Source_three", alertName: "Alert_2"}, 
  {name: "Source_three", alertName: "Alert_2"}, 
  {name: "Source_two", alertName: "Alert_1"}, 
  {name: "Source_three", alertName: "Alert_3"} 
];

下面是具体的实现代码：

const result = array.reduce((acc, current) => {
  // 先检查当前来源是否已经在累加器中存在
  const sourceEntry = acc.find(item => item.name === current.name);
  
  if (sourceEntry) {
    // 检查当前告警是否属于该来源的已统计告警
    const alertEntry = sourceEntry.alerts.find(alert => alert.alertName === current.alertName);
    if (alertEntry) {
      // 已存在则频次+1
      alertEntry.frequency++;
    } else {
      // 不存在则新增告警条目，初始频次为1
      sourceEntry.alerts.push({
        alertName: current.alertName,
        frequency: 1
      });
    }
  } else {
    // 来源不存在则新增来源条目，同时添加第一个告警记录
    acc.push({
      name: current.name,
      alerts: [{
        alertName: current.alertName,
        frequency: 1
      }]
    });
  }
  
  return acc;
}, []);

console.log(result);

逻辑说明 #

• 用reduce初始化一个空数组作为累加器acc，用来存储最终的结构化结果
• 遍历数组每一项时，分三步处理：
  1. 校验当前来源是否已被记录
  2. 若来源已存在，再校验对应告警是否已统计
  3. 存在则频次递增，不存在则新增记录；来源未存在则直接创建新的来源+告警组合

最终输出的结构化结果示例：

[
  {
    "name": "Source_one",
    "alerts": [
      { "alertName": "Alert_1", "frequency": 3 },
      { "alertName": "Alert_3", "frequency": 4 }
    ]
  },
  {
    "name": "Source_three",
    "alerts": [
      { "alertName": "Alert_2", "frequency": 3 },
      { "alertName": "Alert_3", "frequency": 2 },
      { "alertName": "Alert_1", "frequency": 2 }
    ]
  },
  {
    "name": "Source_two",
    "alerts": [
      { "alertName": "Alert_3", "frequency": 2 },
      { "alertName": "Alert_1", "frequency": 3 },
      { "alertName": "Alert_2", "frequency": 3 }
    ]
  }
]

内容的提问来源于stack exchange，提问作者SamK