js实现浮点运算的封装方法

js的浮点运算很不准确，但是可以进行正确的整型运算，所以可以将浮点数变大倍数成整型，运算出结果后再变小原来的倍数。比如0.2+0.3=[(0.2*10)+(0.3*10)]/10=0.5

这里我封装了加减乘除四个方法，在js中进行数值运算时可以直接调用。

module.exports = {
  add: function(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
  },

  sub: function(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
  },

  mul: function(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)
  },

  div: function(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);

  }

}