JS数组格式合并转换

Question

有如下数组var sourceList = [    {SupportProgramId: 1, Category: "AAA", SubCategory: "A-1"},    {SupportProgramId: 2, Category: "AAA", SubCategory: "A-2"},    {SupportProgramId: 3, Category: "AAA", SubCategory: "A-3"},    {SupportProgramId: 4, Category: "BBB", SubCategory: "B-1"},    {SupportProgramId: 5, Category: "CCC", SubCategory: "C-1"},    {SupportProgramId: 6, Category: "CCC", SubCategory: "C-2"}];要求转换成如下格式：求好的转换过程，可以使用es6或lodash提供的方法

Answer 1

供参考

var data = Array.from(sourceList.reduce((map, {

    SupportProgramId: subId, Category: mainTitle, SubCategory: subTitle

  }) => {

  if (map.has(mainTitle)) {

    map.get(mainTitle).subList.push({subId, subTitle})

  } else {

    map.set(mainTitle, {mainTitle, subList: [{subId, subTitle}]})

  }

  return map

}, new Map()).entries())