開發(fā)過程中會遇到j(luò)s精度丟失的問題

0.1 + 0.2 = 0.30000000000000004

常用方法整理

// math 計算 +
  accAdd(num1, num2) {
    num1 = num1.toString().indexOf('.') < 0 ? num1.toString() + '.0' : num1
    num2 = num2.toString().indexOf('.') < 0 ? num2.toString() + '.0' : num2
    let r1 = 0
    let r2 = 0
    let m = 0
    try {
      r1 = num1.toString().split('.')[1].length
    } catch (e) {
      r1 = 0
    }
    try {
      r2 = num2.toString().split('.')[1].length
    } catch (e) {
      r2 = 0
    }
    m = Math.pow(10, Math.max(r1, r2))
    return Math.round(num1 * m + num2 * m) / m
  },
  // -
  accSub(num1, num2) {
    num1 = num1.toString().indexOf('.') < 0 ? num1.toString() + '.0' : num1
    num2 = num2.toString().indexOf('.') < 0 ? num2.toString() + '.0' : num2
    let r1 = 0
    let r2 = 0
    let m = 0
    let n = 0
    try {
      r1 = num1.toString().split('.')[1].length
    } catch (e) {
      r1 = 0
    }
    try {
      r2 = num2.toString().split('.')[1].length
    } catch (e) {
      r2 = 0
    }
    m = Math.pow(10, Math.max(r1, r2))
    n = r1 >= r2 ? r1 : r2
    return (Math.round(num1 * m - num2 * m) / m).toFixed(n)
  },
  // /
  accDiv(num1, num2) {
    num1 = num1.toString().indexOf('.') < 0 ? num1.toString() + '.0' : num1
    num2 = num2.toString().indexOf('.') < 0 ? num2.toString() + '.0' : num2
    let t1 = 0
    let t2 = 0
    let r1 = 0
    let r2 = 0
    try {
      t1 = num1.toString().split('.')[1].length
    } catch (e) {
      t1 = 0
    }
    try {
      t2 = num2.toString().split('.')[1].length
    } catch (e) {
      t2 = 0
    }
    r1 = Number(num1.toString().replace('.', ''))
    r2 = Number(num2.toString().replace('.', ''))
    return (r1 / r2) * Math.pow(10, t2 - t1)
  },
  // *
  accMul(num1, num2) {
    let m = 0
    if (num1 == null) {
      num1 = 0
    }
    let s1 = num1.toString()
    let s2 = num2.toString()
    if (s1.indexOf('.') < 0) s1 += '.0'
    if (s2.indexOf('.') < 0) s2 += '.0'
    try {
      m += s1.split('.')[1].length
    } catch (e) {
      console.log(e)
    }
    try {
      m += s2.split('.')[1].length
    } catch (e) {
      console.log(e)
    }
    return (Number(s1.replace('.', '')) * Number(s2.replace('.', ''))) / Math.pow(10, m)
  },