number-precision，一个js精度计算浮点数的库，但使用中传入异常数据会出现null.toString等的导致程序崩溃的error错误；
    so我决定封装一下

    被除数把null和undefined置为0
    除数的null和undefined置为1

    被成数把null和undefined置为0
    成数的null和undefined置为0

    加减法如果您有使用，可以参看我这个取处理吧~

    // utils.ts

    2. import NP from 'number-precision'
    4. /**
    5.  * 去除null undefined ，NP执行toString导致的error异常
    6.  * 去除 * 0， / 0 导致的NaN
    7.  */
    8. export const NPNoEc = {
    9.   /**
    10.    * 精确除法
    11.    * ---
    12.    * num1 / num2 / other...
    13.    * @param num1
    14.    * @param num2
    15.    * @param others
    16.    * @returns number
    17.    */
    18.   divide: (num1: number, num2: number, ...others: number[]): number => {
    19.     num1 = _.isNil(num1) ? 0 : num1
    20.     num2 = _.isNil(num2) || num2 === 0 ? 1 : num2
    21.     if (others.length > 0) {
    22.       return NPNoEc.divide(NPNoEc.divide(num1, num2), others[0], ...others.slice(1))
    23.     }
    24.     return NP.divide(num1, num2)
    25.   },
    27.   /**
    28.    * 精确乘法
    29.    * ---
    30.    * num1 * num2 * other...
    31.    * @param num1
    32.    * @param num2
    33.    * @param others
    34.    * @returns number
    35.    */
    36.   times: (num1: number, num2: number, ...others: number[]): number => {
    37.     num1 = _.isNil(num1) ? 0 : num1
    38.     num2 = _.isNil(num2) ? 0 : num2
    39.     if (others.length > 0) {
    40.       return NPNoEc.times(NPNoEc.divide(num1, num2), others[0], ...others.slice(1))
    41.     }
    42.     return NP.times(num1, num2)
    43.   }
    44. }

    // utils.test.js

    import { NPNoEc } from './utils'
import NP from 'number-precision'

test('NPNoEc.divide', () => {
  expect(NPNoEc.divide(0, 0)).toBe(0)
  expect(NPNoEc.divide(1, 0)).toBe(1)
  expect(NPNoEc.divide(1, 1)).toBe(1)
  expect(NPNoEc.divide(0, 1)).toBe(0)

  expect(NPNoEc.divide(null, null)).toBe(0)
  expect(NPNoEc.divide(null, 0)).toBe(0)
  expect(NPNoEc.divide(0, null)).toBe(0)

  expect(NPNoEc.divide(undefined, undefined)).toBe(0)
  expect(NPNoEc.divide(null, undefined)).toBe(0)
  expect(NPNoEc.divide(undefined, null)).toBe(0)

  expect(NPNoEc.divide(undefined, 0)).toBe(0)
  expect(NPNoEc.divide(0, undefined)).toBe(0)

  for (let i = 0; i < 100; i++) {
    const num = NPNoEc.divide(i, 100)
    expect(num).not.toBeUndefined()
    expect(num).not.toBeNull()
    expect((num).toString().length).toBeLessThan(8)
  }
});

test('NPNoEc.times', () => {
  expect(NPNoEc.times(0, 0)).toBe(0)
  expect(NPNoEc.times(1, 0)).toBe(1)
  expect(NPNoEc.times(1, 1)).toBe(1)
  expect(NPNoEc.times(0, 1)).toBe(0)

  expect(NPNoEc.times(null, null)).toBe(0)
  expect(NPNoEc.times(null, 0)).toBe(0)
  expect(NPNoEc.times(0, null)).toBe(0)

  expect(NPNoEc.times(undefined, undefined)).toBe(0)
  expect(NPNoEc.times(null, undefined)).toBe(0)
  expect(NPNoEc.times(undefined, null)).toBe(0)

  expect(NPNoEc.times(undefined, 0)).toBe(0)
  expect(NPNoEc.times(0, undefined)).toBe(0)

  for (let i = 0; i < 1; i = NP.plus(i, 0.01)) {
    const num = NPNoEc.times(i, 100)
    expect(num).not.toBeUndefined()
    expect(num).not.toBeNull()
    // expect((i * 100).toString().length).toBeLessThan(8)
    expect((num).toString().length).toBeLessThan(8)
  }
});