js加减乘除精度丢失问题解决

/**

• 解决两个数相加精度丢失问题
• @param a
• @param b
• @returns {Number}
  */

export function floatAdd(a, b) {
  var c, d, e;
  if (undefined == a || null == a || "" == a || isNaN(a)) {
    a = 0;
  }
  if (undefined == b || null == b || "" == b || isNaN(b)) {
    b = 0;
  }
  try {
    c = a.toString().split(".")[1].length;
  } catch (f) {
    c = 0;
  }
  try {
    d = b.toString().split(".")[1].length;
  } catch (f) {
    d = 0;
  }
  e = Math.pow(10, Math.max(c, d));
  return (floatMul(a, e) + floatMul(b, e)) / e;
}

/**

• 解决两个数相减精度丢失问题
• @param a
• @param b
• @returns {Number}
  */

export function floatSub(a, b) {
  var c, d, e;
  if (undefined == a || null == a || "" == a || isNaN(a)) {
    a = 0;
  }
  if (undefined == b || null == b || "" == b || isNaN(b)) {
    b = 0;
  }
  try {
    c = a.toString().split(".")[1].length;
  } catch (f) {
    c = 0;
  }
  try {
    d = b.toString().split(".")[1].length;
  } catch (f) {
    d = 0;
  }
  e = Math.pow(10, Math.max(c, d));
  return (floatMul(a, e) - floatMul(b, e)) / e;
}

/**

• 解决两个数相乘精度丢失问题
• @param a
• @param b
• @returns {Number}
  */

export function floatMul(a = 0, b = 0) {
  var c = 0,
      d = a.toString(),
      e = b.toString();
  try {
    c += d.split(".")[1].length;
  } catch (f) {
  }
  try {
    c += e.split(".")[1].length;
  } catch (f) {
  }
  return Number(d.replace(".", "")) * Number(e.replace(".", "")) / Math.pow(10, c);
}

/**

• 解决两个数相除精度丢失问题
• @param a
• @param b
• @returns
  */

export function floatDiv(a, b) {
  var c, d, e = 0,
      f = 0;
  try {
    e = a.toString().split(".")[1].length;
  } catch (g) {
  }
  try {
    f = b.toString().split(".")[1].length;
  } catch (g) {
  }
  return c = Number(a.toString().replace(".", "")), d = Number(b.toString().replace(".", "")), floatMul(c / d, Math.pow(10, f - e));
}