server/app/extend/context.js

'use strict';
const Decimal = require('decimal.js');
const _ = require('lodash');
// Decimal.set({ precision: 2 });
module.exports = {
  turnDecimal(n) {
    if (_.isObject(n)) {
      n = JSON.parse(JSON.stringify(n));
      if (_.isObject(n)) n = _.get(n, '$numberDecimal');
    }
    return new Decimal(n);
  },
  // 加法
  plus(n1 = 0, n2 = 0) {
    const number1 = this.turnDecimal(n1);
    const number2 = this.turnDecimal(n2);
    const result = number1.add(number2).toFixed(2, Decimal.ROUND_DOWN);
    return this.toNumber(result);
  },
  // 减法
  minus(n1 = 0, n2 = 0) {
    const number1 = this.turnDecimal(n1);
    const number2 = this.turnDecimal(n2);
    const result = number1.minus(number2).toFixed(2, Decimal.ROUND_DOWN);
    return this.toNumber(result);
  },
  // 乘法
  multiply(n1 = 0, n2 = 0) {
    const number1 = this.turnDecimal(n1);
    const number2 = this.turnDecimal(n2);
    const result = number1.mul(number2).toFixed(2, Decimal.ROUND_DOWN);
    return this.toNumber(result);
  },
  // 除法
  divide(n1 = 0, n2 = 0) {
    const number1 = this.turnDecimal(n1);
    const number2 = this.turnDecimal(n2);
    const result = number1.div(number2).toFixed(2, Decimal.ROUND_DOWN);
    return this.toNumber(result);
  },

  toNumber(num) {
    if (_.isObject(num)) {
      num = JSON.parse(JSON.stringify(num));
      if (_.isObject(num)) num = _.get(num, '$numberDecimal');
    }
    return new Decimal(num).toNumber();
  },
};