JS 加减乘除丢失精度问题

 js在加减乘除时对浮点型数据有丢失精度问题 比如 0.1+0.2≠0.3；得到的却是0.300...0004，为了防止这个问题可以用一下方法来处理

export default {
  /**
   * 数字相加
   * @param {*} arg1
   * @param {*} arg2
   * @returns
   */
  accAdd (arg1, arg2) {
    return this.changeNum(arg1, arg2)
  },

  /**
   * 数字相减
   * @param {*} arg1
   * @param {*} arg2
   * @returns
   */
  accSub (arg1, arg2) {
    return this.changeNum(arg1, arg2, false)
  },

  /**
   * 数字相乘
   * @param {*} arg1
   * @param {*} arg2
   * @returns
   */
  accMul (arg1, arg2) {
    let m = 0
    m = this.accAdd(m, this.getDecimalLength(arg1))
    m = this.accAdd(m, this.getDecimalLength(arg2))
    return (this.getNum(arg1) * this.getNum(arg2)) / Math.pow(10, m)
  },

  /**
   * 数字相除
   * @param {*} arg1
   * @param {*} arg2
   * @returns
   */
  accDiv (arg1, arg2) {
    let t1, t2
    t1 = this.getDecimalLength(arg1)
    t2 = this.getDecimalLength(arg2)
    if (t1 - t2 > 0) {
      return this.getNum(arg1) / this.getNum(arg2) / Math.pow(10, t1 - t2)
    } else {
      return (this.getNum(arg1) / this.getNum(arg2)) * Math.pow(10, t2 - t1)
    }
  },

  changeNum (arg1 = '', arg2 = '', isAdd = true) {
    const that = this
    function changeInteger (arg, r, maxR) {
      if (r !== maxR) {
        let addZero = ''
        for (let i = 0; i < maxR - r; i++) {
          addZero += '0'
        }
        arg = Number(arg.toString().replace('.', '') + addZero)
      } else {
        arg = that.getNum(arg)
      }
      return arg
    }
    let r1, r2, maxR, m
    r1 = this.getDecimalLength(arg1)
    r2 = this.getDecimalLength(arg2)
    maxR = Math.max(r1, r2)
    arg1 = changeInteger(arg1, r1, maxR)
    arg2 = changeInteger(arg2, r2, maxR)
    m = Math.pow(10, maxR)
    if (isAdd) {
      return (arg1 + arg2) / m
    } else {
      return (arg1 - arg2) / m
    }
  },

  getDecimalLength (arg = '') {
    try {
      return arg.toString().split('.')[1].length
    } catch (e) {
      return 0
    }
  },

  getNum (arg = '') {
    return Number(arg.toString().replace('.', ''))
  }
}