reduce使用场景记录

 // 求和
  const arr1 = [1, 2, 3]

  const delTotal = arr1.reduce((acc, cur) => {
    return acc + cur
  }, 0)

  // 求最大值
  const delMax = arr1.reduce((acc, cur) => {
    return Math.max(acc, cur)
  }, 0)

  // 将二维数组转化为一维
  const arr2 = [[1, 2, 3], [4, 5, 6]]

  const delFlat = arr2.reduce((acc, cur) => {
    return [...acc, ...cur]
  }, [])

  // 数组去重
  const arr3 = [1, 2, 3, 2, 5, 1]

  const delRepeat = arr3.reduce((acc, cur) => {
    return acc.includes(cur) ? acc : acc.concat(cur)
  }, [])

  // 组合对象
  // https://xxx.com/369991562?age=20&name=zhang
  const getSearchParams = () => {
    const searchPar = window.location.search
    const queryStr = searchPar.split('?')[1]
    const queryList = queryStr.split('&')

    return queryList.reduce((acc, cur) => {
      const tempArr = cur.split('=')
      return {
        ...acc,
        [tempArr[0]]: decodeURI(tempArr[1])
      }
    }, {})
  }

// 数组分组
const people = [
  { name: 'Alice', gender: 'female' },
  { name: 'Bob', gender: 'male' },
  { name: 'Charlie', gender: 'male' },
  { name: 'Diana', gender: 'female' }
]

const groups = people.reduce((acc, curr) => {
  const key = curr.gender
  if (!acc[key]) {
    acc[key] = []
  }
  acc[key].push(curr)
  return acc
}, {})

// 对象筛选
const testMap = {
  'test1': '测试1',
  'test2': '测试2'
}

const dataTest = {
  'test1': [{ name: 'zhangsan', age: 20 }],
  'test2': [{ name: 'lisi', age: 30 }],
  'test3': [{ name: 'wangwu', age: 40 }]
}

const dataKeys = Object.keys(dataTest)
const resultData = Object.keys(testMap).reduce((acc, curr) => {
  if (dataKeys.includes(curr)) {
    acc[curr] = dataTest[curr]
  }
  return acc
}, {})