Koa2.5 做图片服务器转发解决跨域最佳实战

背景：

跨域报错如下：

1597:1 Access to Image at 'https://xxx.com/static/image/[email protected]?' 
from origin 'https://xxx.com' has been blocked by CORS policy: 
No 'Access-Control-Allow-Origin' header is present on the requested 
resource. Origin 'https://xxx.com' is therefore not allowed access.

实战：

按照必须的依赖包：主要是request module：

$ npm i -D koa koa-router request

那我们就做一个转发服务器吧：

/**
 * Created by happy on 4/10/18.
 */
var Koa = require('koa');
var Router = require('koa-router');
var request = require('request');

var app = new Koa();
var router = new Router();
var port = 7788;

router.get('/', (ctx, next) => {
  ctx.body = 'hello';
});

// 这里是愉快的做静态资源转发
router.get('/static', (ctx, next) => {
  ctx.body = request.get(ctx.url.replace('/image?', ''));
});

app
  .use(router.routes())
  .use(router.allowedMethods())
  .listen(port, () => console.log(`✅  The server is running at http://localhost:${port}`));

// 访问：localhost:7788/static?xxx跨域服务器资源

总结：

本来准备使用fetch获取文件流，奈何看了官网所有API尝试皆以失败告知，故使用request获取文件流。