Calculation/app/public/js/zh_calc.js

'use strict';

/**
 *
 * @author Mai
 * @date
 * @version
 */
;const baseCalc = (function () {
    const mulPrecision = 12, divPrecision = 12;

    function digitLength (num) {
        // 兼容科学计数
        var eSplit = num.toString().split(/[eE]/);
        var len = (eSplit[0].split('.')[1] || '').length - (+(eSplit[1] || 0));
        return len > 0 ? len : 0;
    }

    function powLength (num) {
        var rs = num.toString();
        if (rs.indexOf('+') > 0) {
            return rs.match(/0*$/g).length();
        } else {
            const eSplit = rs.split(/[eE]/);
            const len = Number(eSplit[1]) - this.digitLength(eSplit[0]);
            return len > 0 ? len : 0;
        }
    }

    function round (num, digit) {
        return Math.round(num * Math.pow(10, digit)) / Math.pow(10, digit);
    }

    function add(num1, num2) {
        var d1 = this.digitLength(num1), d2 = this.digitLength(num2);
        return this.round(num1 + num2, Math.max(d1, d2));
    }

    function sub(num1, num2) {
        var d1 = this.digitLength(num1), d2 = this.digitLength(num2);
        return this.round(num1 - num2, Math.max(d1, d2));
    }

    function mul(num1, num2) {
        return this.round(num1 * num2, mulPrecision);
    }

    function div(num1, num2) {
        return this.round(num1 / num2, divPrecision);
    }

    return { digitLength: digitLength, powLength: powLength, round: round, add: add, sub: sub, mul: mul, div: div }
})();

/**
 * 计算(四则、舍入) 统一，方便以后置换
 * @type {{add, sub, mul, div, round}}
 */
const ZhCalc = (function () {
    /**
     * 加法 num1 + num2
     * @param num1
     * @param num2
     * @returns {number}
     */
    function add(num1, num2) {
        return baseCalc.add(num1 ? num1 : 0, num2 ? num2: 0);
    };
    /**
     * 减法 num1 - num2
     * @param num1
     * @param num2
     * @returns {number}
     */
    function sub(num1, num2) {
        return baseCalc.sub(num1 ? num1 : 0, num2 ? num2 : 0);
    };
    /**
     * 乘法 num1 * num2
     * @param num1
     * @param num2
     * @returns {*}
     */
    function mul(num1, num2, digit = 6) {
        return Decimal.mul(num1 ? num1 : 0, num2 ? num2 : 0).toDecimalPlaces(digit).toNumber();
    };
    /**
     * 除法 num1 / num2
     * @param num1 - 被除数
     * @param num2 - 除数
     * @returns {*}
     */
    function div(num1, num2, digit = 6) {
        if (num2 && !checkZero(num2)) {
            return Decimal.div(num1 ? num1: 0, num2).toDecimalPlaces(digit).toNumber();
        } else {
            return null;
        }
    };
    /**
     * 四舍五入
     * @param {Number} value - 舍入的数字
     * @param {Number} decimal - 要保留的小数位数
     * @returns {*}
     */
    function round(value, decimal) {
        return value ? Decimal.round(value, decimal).toNumber() : null;
    };
    return {add, sub, mul, div, round}
})();