simple-utils-js/src/function/calcFn.js

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/**
 * @description: 加减乘除运算
 * @param {*}
 * @return {*}
 */

const calcFn = {
  add() {
    let arg = Array.from(arguments)
    return arg.reduce((total, num) => {
      return accAdd(total, num)
    })
  },
  sub() {
    let arg = Array.from(arguments)
    return arg.reduce((total, num) => {
      return accAdd(total, -num)
    })
  },
  mul() {
    let arg = Array.from(arguments)
    return arg.reduce((total, num) => {
      return accMul(total, num)
    })
  },
  div() {
    let arg = Array.from(arguments)
    return arg.reduce((total, num) => {
      return accDiv(total, num)
    })
  },
}
function accAdd(arg1, arg2) {
  var r1, r2, m
  try {
    r1 = arg1.toString().split('.')[1].length
  } catch (e) {
    r1 = 0
  }
  try {
    r2 = arg2.toString().split('.')[1].length
  } catch (e) {
    r2 = 0
  }
  m = Math.pow(10, Math.max(r1, r2))
  return (arg1 * m + arg2 * m) / m
}

//说明：javascript的乘法结果会有误差，在两个浮点数相乘的时候会比较明显。这个函数返回较为精确的乘法结果。
//调用：accMul(arg1,arg2)
//返回值：arg1乘以arg2的精确结果
function accMul(arg1, arg2) {
  var m = 0,
    s1 = arg1.toString(),
    s2 = arg2.toString()
  try {
    m += s1.split('.')[1].length
  } catch (e) {}
  try {
    m += s2.split('.')[1].length
  } catch (e) {}
  return (Number(s1.replace('.', '')) * Number(s2.replace('.', ''))) / Math.pow(10, m)
}

//说明：javascript的除法结果会有误差，在两个浮点数相除的时候会比较明显。这个函数返回较为精确的除法结果。
//调用：accDiv(arg1,arg2)
//返回值：arg1除以arg2的精确结果
function accDiv(arg1, arg2) {
  var t1 = 0,
    t2 = 0,
    r1,
    r2
  try {
    t1 = arg1.toString().split('.')[1].length
  } catch (e) {}
  try {
    t2 = arg2.toString().split('.')[1].length
  } catch (e) {}
  r1 = Number(arg1.toString().replace('.', ''))
  r2 = Number(arg2.toString().replace('.', ''))
  return (r1 / r2) * Math.pow(10, t2 - t1)
}

module.exports = calcFn