app.js

const koa = require("koa");  
const bodyParser = require("koa-bodyparser"); //表单解析中间件
const router = require("koa-router");     //路由中间件
const cors = require("koa2-cors");
const app = new koa();

//配置跨域中间件
app.use(cors({
    origin: function(ctx) {
      // if (ctx.url === '/test') {
      //   return false;
      // }
      return 'http://localhost:3000';
    },
    // exposeHeaders: ['WWW-Authenticate', 'Server-Authorization'],
    // maxAge: 5,
    credentials: true,
    allowMethods: ['GET', 'POST', 'DELETE'],
    // allowHeaders: ['Content-Type', 'Authorization', 'Accept'],
  }));

//使用表单解析中间件
app.use(bodyParser({
    "formLimit":"5mb",
    "jsonLimit":"5mb",
    "textLimit":"5mb"
}));

app.use(require('./routers/proxy.js').routes())

//监听在8080端口
app.listen(3101) 

console.log(`listening on port 3101`)