koa2.x訪問網絡圖片並保存到本地

const router = require('koa-router')()
const request = require('koa2-request')
var fs = require("fs");
var comData = require('../public/javascripts/comonData.js');
var comicUrl = 'https://mhpic.jumanhua.com';

router.get('/save', async (ctx, next) => {
    var chapter = ctx.query.id;
    var comic_chapter = comData.comicList;
    if (chapter) {
        var index = comic_chapter.length-(Number(chapter) + 1);
        var currentChapter = comic_chapter[index];
        var i,loadUrl, filename,
            startnum = currentChapter.start_num;
        var endnum = currentChapter.end_num;
        var url = currentChapter.rule.split('$$')[0];
        for (i = startnum; i < endnum+1; i++ ) {
            loadUrl = `${comicUrl}${url}${i}.jpg-mht.low.webp`; // 圖片的網絡地址
            filename = `${chapter}_${i}`;
            const path = `public/images/${filename}.jpg`;
            request.get({uri:encodeURI(loadUrl), encoding:'binary'},function(err,res) {
                if (!err) {
                    fs.writeFile(path, res.body, "binary", function (err, res) {
                        if (!err) {
                            console.log('成功！')
                        } else {
                            console.log(err);
                        }
                    })
                }
            })
        }
        ctx.body = {
            code: 200,
            msg: '保存成功！'
        }
    } else {
        ctx.body = {
            code: 200,
            msg: '請輸入需要保存的章節'
        }
    }
})