xms-basic-util/src/ringCenter/sumQuarter.js

js基础工具类集合,集成方便后期调用，通过webpack编译，支持多种平台，如es6、node、浏览器引入等 ## 使用 ### es6方法 - 安装 ``` npm install xms-basic-util ``` - 导入 ``` import xmsBasicUtil from 'xms-basic-util' //日期转换工具对象 const dateFormat = xmsBasicUtil.dateFormat; //数字处理工具对象 const mathUtil = xmsBasicUt

/**
 * 针对数字运算解决、兼容了数字精度丢失问题
 * @type {*[]}
 */
// 测试数据
const saleItems = [
  { month: 1, date: 1, transationId: '1', salePrice: 100.22 },
  { month: 1, date: 2, transationId: '2', salePrice: 102.01 },
  { month: 5, date: 3, transationId: '3', salePrice: 1020.99 },
  { month: 3, date: 1, transationId: '4', salePrice: 89.22 },
  { month: 12, date: 1, transationId: '5', salePrice: 78.45 },
  { month: 9, date: 2, transationId: '6', salePrice: 343.22 },
  { month: 9, date: 2, transationId: '7', salePrice: 23.01 },
  { month: 10, date: 3, transationId: '8', salePrice: 11.11 }
]

/**
 * 计算季度销量
 * @param saleItems
 * @returns {[]}
 */
function sumByQuarter (saleItems) {
  const array = []
  const quarterMap = {}
  saleItems.forEach(item => {
    const quarter = parseInt((item.month - 1) / 3) + 1
    quarterMap[quarter] = quarterMap[quarter] || []
    quarterMap[quarter].push(item)
  })

  for (const quarter in quarterMap) {
    const value = quarterMap[quarter]
    const transactionNums = value.length
    const totalPrices = value.reduce((prev, cur) => {
      return math.accAdd(prev, cur.salePrice)
    }, 0)

    array.push({
      quarter: quarter,
      totalPrices: totalPrices,
      transactionNums: transactionNums
    })
  }

  return array
}

/**
 * 计算季度平均销量
 * @param saleItems
 * @returns {*|*[]}
 */
function averageByQuarter (saleItems) {
  let array = sumByQuarter(saleItems)
  array.forEach(item => {
    item.totalPrices = math.accDiv(item.totalPrices, item.transactionNums, 2)
  })
  // 属性名替换
  array = JSON.parse(JSON.stringify(array).replace(/totalPrices/g, 'averagePrices'))
  return array
}

/**
 * 数字运算
 */
const math = {
  /**
   * 除法 解决数字精度丢失
   * @param arg1
   * @param arg2
   * @param decimals 保留小数的位数
   * @returns {number|*}
   */
  accDiv (arg1, arg2, decimals) {
    const [t1, t2] = this.getDitLength(arg1, arg2)
    const num = Number((this.decimalToInt(arg1) / this.decimalToInt(arg2)) * Math.pow(10, t2 - t1))
    return this.decimalsFormat(num, decimals)
  },
  /**
   * 加法
   * @param arg1
   * @param arg2
   * @returns {number|*}
   */
  accAdd (arg1, arg2) {
    const [r1, r2] = this.getDitLength(arg1, arg2)
    const m = Math.pow(10, Math.max(r1, r2))
    return this.accDiv((this.accMul(arg1, m) + this.accMul(arg2, m)), m, 2)
  },
  /**
   * 乘法
   * @param arg1
   * @param arg2
   * @param decimals 保留小数的位数
   * @returns {number|*}
   */
  accMul (arg1, arg2, decimals) {
    const [r1, r2] = this.getDitLength(arg1, arg2)
    const m = r1 + r2
    const num = this.decimalToInt(arg1) * this.decimalToInt(arg2) / Math.pow(10, m)
    return this.decimalsFormat(num, decimals)
  },
  /**
   * 获取小数点的位数
   * @param arg1
   * @param arg2
   * @returns {[number, number]}
   */
  getDitLength (arg1, arg2) {
    let r1, r2
    try {
      r1 = arg1.toString().split('.')[1].length
    } catch (e) {
      r1 = 0
    }

    try {
      r2 = arg2.toString().split('.')[1].length
    } catch (e) {
      r2 = 0
    }
    return [r1, r2]
  },
  /**
   * 保留小数位
   * @param num
   * @param decimals
   * @returns {number}
   */
  decimalsFormat (num, decimals) {
    if (decimals != undefined && decimals >= 0) {
      num = Math.round(num * Math.pow(10, decimals)) / Math.pow(10, decimals)
    }
    return num
  },
  /**
   * 去掉小数点
   * @param param
   * @returns {number}
   */
  decimalToInt (param) {
    return Number(param.toString().replace('.', ''))
  }
}

// 计算季度销量
console.log('sumByQuarter:%o', sumByQuarter(saleItems))
// 计算季度平均销量
console.log('averageByQuarter:%o', averageByQuarter(saleItems))