js 精确计算(加减乘除)

js 精确计算(加减乘除)

• 工具类CalcUtil.js

class CalcUtil {
  // 两数相加
  calcAdd(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;
  }
  // 两数相减
  calcSub(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 ((num1 * m - num2 * m) / m).toFixed(n);
  }
  // 两数相乘
  calcMult(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);
  }
  // 两数相除
  calcDiv(num1, num2) {
    var t1 = 0,
      t2 = 0,
      r1,
      r2;
    try {
      t1 = num1.toString().split('.')[1].length;
    } catch (e) {}
    try {
      t2 = num2.toString().split('.')[1].length;
    } catch (e) {}
    r1 = Number(num1.toString().replace('.', ''));
    r2 = Number(num2.toString().replace('.', ''));
    return (r1 / r2) * Math.pow(10, t2 - t1);
  }
}

export default new CalcUtil();