说明：在js计算过程中小数计算很容易出现精度问题，比如典型的0.1 + 0.2。 在之前的包里面，他们很多都是将小数乘以一定的倍数，比如555.30乘以100，然后再进行计算，但是大家可以尝试一下555.30 乘以 100也会出现精度问题，所以，一些包在这种情况下会出错。这个包规避了这个问题。

Introduction: It is easy to make mistakes when we calculate decimal, for example, 0.1 + 0.2 !== 0.3 There are some packages to resolve this problem, but you can see their code. They multiply decimals by 10 ^ n (n is a integer), then they get a integer, at last they use the integer to calculate with the integer. Isn't it right? It is right in most cases, but you can try this, '555.30 * 100'. We can't get a integer by multiplying decimals by 10 ^ n. The result is 55529.99999999999. So in this case, there packages will make mistakes. sg-calc, this package aims at resolving this problem.

使用方法

安装 installation

npm i sg-calc --save -dev 
或者 or
yarn add sg-calc

引入 import

const sg_calc = require('sg-calc')

或者 or

import sg_calc from 'sg-calc'

1、 加法 addition

const res1 = sg_calc.add(0.1, 0.2) // 0.3

2、 减法 subtraction

const res2 = sg_calc.minus(0.3, 0.1) // 0.2

3、 乘法 multiply

const res3 = sg_calc.multiply(55.551, 100) // 5555.1

4、 除法 division

const res4 = sg_calc.divide(0.3, 0.1) // 3

5、链式调用 chained invoking 如果存在多次计算的话，那么可能会形成多层嵌套的结构如：sg_calc.divide(sg_calc.multiply(55.551, 100), 0.1)， 这样在层级过深的情况下显得不太好阅读和使用，因此可以尝试一下链式调用 开始调用链式结构去计算需先使用sg_calc.start(num)去初始化，当你要获取结果得时候，使用end()函数去获取结果:

if there are so many calculations, This can result in a multi-layered nested structure, like sg_calc.divide(sg_calc.multiply(55.551, 100), 0.1), as you can see, It is not easy to ready or use. so you can try the chained invoking. At first, wo need to use 'sg_calc.start(num)' to init, when you want to get the result, you just need to use '.end()' to get the result.

const res5 = sg_calc.start(0.1).add(0.2).multiply(3).end() // 0.9