SpringBoot-13-插曲之Node文件重命名+自动生成json对象

[1]有很多图片放服务器里，怎么能更好的管理，更方便拿到图片呢?
[2]想用json 以一个对象数组的形式保存这些图片：以[{img:"图片名"},{img:"图片名"}....]形式
[3]虽说想法是很好，但不可能一条一条自己写吧，好歹咱也是21世纪敲代码的人。
[4]刚好最近学了点node,就拿来小试牛刀。

const fs = require('fs');
const path = require('path');

let result = read('F:/SpringBootFiles/Image');
function read(pathName) {
    let objs = [];
    //读取路径,返回所有文件节点=文件夹+文件
    let filePath = "F:/SpringBootFiles/Image/img.json";//输出路径
    fs.readdir(pathName, (err, files) => {//读文件夹
        for (let file of files) {//遍历文件
            let oldName = path.join('F:/SpringBootFiles/Image', file);//文件旧路径
            let extname = path.extname(file);//文件后缀名
            let basename = path.basename(file,extname);//文件名除去后缀(这里没有到，提一下)
            let newName = rangeChar(16, true) + extname;//新名称，随机获取16个字符
            fs.rename(oldName, path.join('F:/SpringBootFiles/Image', newName), err => {});//重命名

            let obj = {};//定义对象
            obj.img = newName;//该对象img属性为新文件名称
            objs.push(obj);//将对象添到数组中
        }

        fs.writeFileSync(filePath, JSON.stringify(objs), {encoding: 'utf8'})//写入数据
    });

    function rangeChar(len, hasBig = false) {
        let allLen = 25;
        let chars = ["a", "b", "c", "d", "e", "f", "g",
            "h", "i", "j", "k", "l", "m", "n",
            "o", "p", "q", "r", "s", "t",
            "u", "v", "w", "x", "y", "z"];
        let charsBig = chars.map(item => item.toUpperCase());

        if (hasBig) {
            chars = chars.concat(charsBig);
            allLen = 49;
        }
        let result = [];
        for (let i = 0; i < len; i++) {
            let char = chars[rangeInt(0, allLen)];
            result.push(char);
        }
        return result.join('');
    };

    function rangeInt(s, e) {
        let max = Math.max(s, e);
        let min = Math.min(s, e) - 1;
        return min + Math.ceil(Math.random() * (max - min));
    };