Js precision processing

division

 bcDiv(arg1, arg2, decimal = 2) {
    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) { }
    Math.r1 = Number(arg1.toString().replace(".".""))
    Math.r2 = Number(arg2.toString().replace(".".""))
    return this.bcMul((Math.r1 / Math.r2), Math.pow(10, t2 - t1), decimal);
  },
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The multiplication

  bcMul(arg1, arg2, decimal = 2) {
    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 this.formatDecimal(Number(s1.replace("."."")) * Number(s2.replace("."."")) / Math.pow(10, m), decimal)
  },
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add

  bcAdd(arg1, arg2, decimal = 2) {
    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 this.formatDecimal((arg1 * m + arg2 * m) / m, decimal)
  },
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subtraction

 bcSub(arg1, arg2, decimal = 2) {
    var r1, r2, m, n;
    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));
    n = (r1 >= r2) ? r1 : r2;
    return this.formatDecimal(((arg1 * m - arg2 * m) / m).toFixed(n), decimal);
  },
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Keep two decimal places (no rounding)

formatDecimal(num, decimal) {
    num = num.toString();
    let index = num.indexOf(".");
    if(index ! = = -1) {
      num = num.substring(0, decimal + index + 1);
    } else {
      num = num.substring(0);
    }
    return parseFloat(num).toFixed(decimal);
  },
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