如何将 DRY 概念应用于重复的数组映射任务？

Question

鉴于以下代码...

// last 7 days data from db ...

let last7Days =
  result.map((data) => data._id).slice(1).slice(-7);

let last7daysIncome =
  result.map((data) => data.totalIncomeAmount).slice(1).slice(-7);

let last7daysAvgIncome =
  result.map((data)=> data.avrageIncome).slice(1).slice(-7);

let last7daysPatientionsCount =
  result.map((data)=> data.PatientionsCount).slice(1).slice(-7);

let last7disease =
  result.map((data)=>data.diseaseArr).slice(1).slice(-7);

...如何使用 JavaScript 中的DRY 概念（D on't Repeat Y ourself ）来简化这段代码？

Answer 1

创建一个函数，发送要提取的字段的参数，甚至是要回溯的天数：

function lastDays(result, field, days) {
  return result.slice(days).map((data)=>data[field]);  
}
function lastSevenDays(result, field) {
  return lastDays(result, field, -7);
}

let last7Days = lastSevenDays(result, "_id")
let last7daysIncome = lastSevenDays(result, "totalIncomeAmount")
let last7daysAvgIncome  =lastSevenDays(result, "avrageIncome")
let last7daysPatientionsCount  = lastSevenDays(result, "PatientionsCount")
let last7disease = lastSevenDays(result, "diseaseArr")