tools-for-js/lib/utils/calculate.js

基于babel构建的JavaScript前端工具库

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.summation = exports.exactAdd = exports.countNumber = void 0;
/**
 * @description: 精确加法：
 * js的加法结果会有丢失精度的情况，例如两个浮点数相加的时候
 * @author: 琴时
 * @param {Number|String} arg1
 * @param {Number|String} arg2
 * @return {Number}
 */
var exactAdd = exports.exactAdd = function exactAdd(arg1, arg2) {
  if (isNaN(arg1)) arg1 = 0;
  if (isNaN(arg2)) arg2 = 0;
  arg1 = Number(arg1);
  arg2 = Number(arg2);
  var r1, r2, m, c;
  try {
    r1 = arg1.toString().split('.')[1].length;
  } catch (e) {
    r1 = 0;
  }
  try {
    r2 = arg2.toString().split('.')[1].length;
  } catch (e) {
    r2 = 0;
  }
  c = Math.abs(r1 - r2);
  m = Math.pow(10, Math.max(r1, r2));
  if (c > 0) {
    var cm = Math.pow(10, c);
    if (r1 > r2) {
      arg1 = Number(arg1.toString().replace('.', ''));
      arg2 = Number(arg2.toString().replace('.', '')) * cm;
    } else {
      arg1 = Number(arg1.toString().replace('.', '')) * cm;
      arg2 = Number(arg2.toString().replace('.', ''));
    }
  } else {
    arg1 = Number(arg1.toString().replace('.', ''));
    arg2 = Number(arg2.toString().replace('.', ''));
  }
  return (arg1 + arg2) / m;
};
/*******
 * @description: 计算数组元素的和
 * @author: 琴时
 * @param {Array} list
 * @return {Number}
 */
var summation = exports.summation = function summation(list) {
  var sum = 0;
  if (list && list.length > 0) {
    sum = list.reduce(function (n, m) {
      return exactAdd(n, m);
    });
  }
  return sum;
};

/*******
 * @description: 计算两个参数
 * @param {Number|String} arg1
 * @param {Number|String} arg2
 * @param {String} type [计算类型:sum-加,subtract-减,multiply-乘,divide-除]
 * @return {Number}
 */
var countNumber = exports.countNumber = function countNumber(arg1, arg2) {
  var type = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : 'sum';
  if (arg1 === undefined || arg2 === undefined) {
    console.log('参数格式不正确');
    return NaN;
  }
  if (isNaN(arg1)) arg1 = 0;
  if (isNaN(arg2)) arg2 = 0;

  // 转字符串类型
  arg1 = arg1.toString();
  arg2 = arg2.toString();

  // 获取小数点位置
  var index1 = arg1.indexOf('.');
  var index2 = arg2.indexOf('.');

  // 获取小数点位数
  var ws1 = 0;
  var ws2 = 0;
  if (index1 !== -1) {
    ws1 = arg1.split('.')[1].length;
  }
  if (index2 !== -1) {
    ws2 = arg2.split('.')[1].length;
  }
  var bigger = ws1 > ws2 ? ws1 : ws2; //位数较大值
  var small = ws1 < ws2 ? ws1 : ws2; //位数较小值
  var zeroCount = bigger - small; //位数差

  // 去除小数点
  arg1 = arg1.replace('.', '');
  arg2 = arg2.replace('.', '');

  // 位数差额补0
  if (ws1 === small) {
    for (var i = 0; i < zeroCount; i++) {
      arg1 += '0';
    }
  } else {
    for (var _i = 0; _i < zeroCount; _i++) {
      arg2 += '0';
    }
  }
  var result = 0; //结果
  var multiple = 1; //倍数
  for (var _i2 = 0; _i2 < bigger; _i2++) {
    multiple = multiple * 10;
  }

  // 计算结果
  if (type === 'sum') {
    result = parseInt(arg1) + parseInt(arg2);
    result = result / multiple;
  } else if (type === 'subtract') {
    result = parseInt(arg1) - parseInt(arg2);
    result = result / multiple;
  } else if (type === 'multiply') {
    result = parseInt(arg1) * parseInt(arg2);
    result = result / multiple / multiple;
  } else if (type === 'divide') {
    result = parseInt(arg1) / parseInt(arg2);
  }
  return result;
};