const koa = require('koa');
const request = require('request');
const fs = require('fs');
const path = require('path');
function requestAsync(url) {
    return new Promise((resolve, reject) => {
        request({
            url: url
        }, (err, res, body) => {
            if (err) {
                reject(err);
            } else {
                resolve(body);
            }
        })
    });
}
function writeFileAsync(path, data, option) {
    return new Promise((resolve, reject) => {
        fs.writeFile(path, data, option, (err)=> {
            if (err) {
                reject(err);
            } else {
                resolve();
            }
        })
    });
}
const app = new koa();
app.use(async (ctx) => {
    let url = 'http://pubimage.360doc.com/index7/bannerl_1.jpg';
    let filepath = path.join(__dirname, './images/详情');
    filepath = filepath + '/1.jpg';
    // request(url).pipe(fs.createWriteStream(filepath));这个可以正常抓取图片
    let data = await requestAsync(url);
    let buffer = Buffer.from(data);
    await writeFileAsync(filepath, buffer);
    ctx.type = 'jpg';
    ctx.body = buffer;
})
app.listen(3000);
console.log(`starting at ${3000}`);

我把request 和 writefile 都写成了promise的形式，抓取html是可以的，抓取图片就不行了

一开始data 输出是string类型，也就是request 的body是string类型，我就使用Buffer.from

转为buffer类型，也是不行，改为Buffer.from(data, 'base64')也是不行，但就是使用 request(url).pipe(fs.createWriteStream(filepath))就可以
请问一下哪里出错了