一维数组，带有父子级关联属性的一维数组转化成嵌套数组，或者转化成树

一维数组，带有父子级关联属性的一维数组转化成嵌套数组，或者转化成树

一、源数组

let a = [
  {
    parentMeasure: null, // 为空则没有父表头
    measure: '指标1'
  },
  {
    parentMeasure: '指标1', // 父表头为指标1
    measure: '指标2'
  },
  {
    parentMeasure: '指标1',
    measure: '指标3'
  },
  {
    parentMeasure: '指标3',
    measure: '指标4'
  },
  {
    parentMeasure: '指标3',
    measure: '指标5'
  },
  {
    parentMeasure: '', // 为空则没有父表头
    measure: '指标6'
  }
]

二、目标嵌套数组（树）

let res = [
  {
    parentMeasure: null,
    measure: '指标1',
    children: [
      { parentMeasure: '指标1', measure: '指标2' },
      {
        parentMeasure: '指标1',
        measure: '指标3',
        children: [
          { parentMeasure: '指标3', measure: '指标4' },
          { parentMeasure: '指标3', measure: '指标5' }
        ]
      }
    ]
  },
  { parentMeasure: '', measure: '指标6' }
]

三、实现

// 找出一级表头
let tree = a.filter(it => !it.parentMeasure)
function convert(arr) {
  arr &&
    arr.forEach(it => {
      let p = it.measure
      let children = a.filter(item => item.parentMeasure === p)
      if (children && children.length > 0) {
        it.children = children
        convert(it.children)
      }
    })
}

convert(tree)