js精准浮点计算

转--记录

// 两个浮点数求和
var accAdd = function(num1, num2) {
  var r1, r2, m
  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 (num1*m+num2*m)/m;
  return Math.round(num1 * m + num2 * m) / m
}

// 两个浮点数相减
var accSub = function(num1, num2) {
  var r1, r2, m, n
  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)
}
// 两数相除
var accDiv = function(num1, num2) {
  var t1, t2, r1, r2
  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)
}
//乘法
var accMul = function(num1, num2) {
  var m = 0,
    s1 = num1.toString(),
    s2 = num2.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)
}