解决js加减乘除精度丢失问题

公共类, 将科学计数法的数字转为字符串(以下加减乘除依赖该方法)

var toNonExponential = (num)=> {
    if(num == null) {
        return num;
    }
    if(typeof num == "number") {
        var m = num.toExponential().match(/\d(?:\.(\d*))?e([+-]\d+)/);
        return num.toFixed(Math.max(0, (m[1] || '').length - m[2]));
    }else {
        return num;
    }
 }
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乘(以下加减除依赖该方法)

var floatMultiply = (arg1, arg2) => {
    arg1 = Number(arg1);
    arg2 = Number(arg2);
    if ((!arg1 && arg1!==0) || (!arg2 && arg2!==0)) {
        return null;
    }
    arg1 = toNonExponential(arg1);
    arg2 = toNonExponential(arg2);
    var n1, n2;
    var r1, r2; // 小数位数
    try {
        r1 = arg1.toString().split(".")[1].length;
    } catch (e) {
        r1 = 0;
    }
    try {
        r2 = arg2.toString().split(".")[1].length;
    } catch (e) {
        r2 = 0;
    }
    n1 = Number(arg1.toString().replace(".", ""));
    n2 = Number(arg2.toString().replace(".", ""));
    return n1 * n2 / Math.pow(10, r1 + r2);
}
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除

var floatDivide = (arg1, arg2) => {
    arg1 = Number(arg1);
    arg2 = Number(arg2);
    if (!arg2) {
        return null;
    }
    if (!arg1 && arg1!==0) {
        return null;
    }else if(arg1===0) {
        return 0;
    }
    arg1 = toNonExponential(arg1);
    arg2 = toNonExponential(arg2);
    var n1, n2;
    var r1, r2; // 小数位数
    try {
        r1 = arg1.toString().split(".")[1].length;
    } catch (e) {
        r1 = 0;
    }
    try {
        r2 = arg2.toString().split(".")[1].length;
    } catch (e) {
        r2 = 0;
    }
    n1 = Number(arg1.toString().replace(".", ""));
    n2 = Number(arg2.toString().replace(".", ""));
    return floatMultiply((n1 / n2), Math.pow(10, r2 - r1));
}
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加

var floatAdd = (arg1, arg2) => {
    arg1 = Number(arg1) || 0;
    arg2 = Number(arg2) || 0;
    arg1 = toNonExponential(arg1);
    arg2 = toNonExponential(arg2);
    var r1, r2, m;
    try {
        r1 = arg1.toString().split(".")[1].length;
    } catch (e) {
        r1 = 0;
    }
    try {
        r2 = arg2.toString().split(".")[1].length;
    } catch (e) {
        r2 = 0;
    }
    m = Math.pow(10, Math.max(r1, r2));
    return (floatMultiply(arg1, m) + floatMultiply(arg2, m)) / m;
}
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减

var floatSub = (arg1, arg2) => {
    arg1 = Number(arg1) || 0;
    arg2 = Number(arg2) || 0;
    arg1 = toNonExponential(arg1);
    arg2 = toNonExponential(arg2);
    var r1, r2, m, n;
    try {
        r1 = arg1.toString().split(".")[1].length;
    } catch (e) {
        r1 = 0;
    }
    try {
        r2 = arg2.toString().split(".")[1].length;
    } catch (e) {
        r2 = 0;
    }
    m = Math.pow(10, Math.max(r1, r2));
    // 动态控制精度长度
    n = (r1 >= r2) ? r1 : r2;
    return ((floatMultiply(arg1, m) - floatMultiply(arg2, m)) / m).toFixed(n);
}
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参考:https://blog.csdn.net/ycclydy/article/details/123580326