js运算失去精度问题解决

使用big.js库
http://mikemcl.github.io/big.js/

$ npm install big.js

import Big from 'big.js';

x = new Big(123.4567)
y = Big('123456.7e-3')                 // 'new' is optional
z = new Big(x)
x.eq(y) && x.eq(z) && y.eq(z)          // true

Big.strict = true
x = new Big(1)                         // TypeError: [big.js] Invalid number
y = new Big('1.0000000000000001')
y.toNumber()                           // Error: [big.js] Imprecise conversion

0.3 - 0.1                              // 0.19999999999999998
x = new Big(0.3)
x.minus(0.1)                           // "0.2"
x                                      // "0.3"

x = new Big(255.5)
x.toExponential(5)                     // "2.55500e+2"
x.toFixed(5)                           // "255.50000"
x.toPrecision(5)                       // "255.50"

Big.DP = 10
Big.RM = Big.roundHalfUp

x = new Big(2);
y = new Big(3);
z = x.div(y)                           // "0.6666666667"
z.sqrt()                               // "0.8164965809"
z.pow(-3)                              // "3.3749999995"
z.times(z)                             // "0.44444444448888888889"
z.times(z).round(10)                   // "0.4444444445"