如何使用 koa 允许 Access-Control-Allow-Origin

Question

我是 Koa 新手，遇到了一个使用 epxress 时没有遇到的问题。

这是我的代码：

const koa = require("koa");
const koaRouter = require("koa-router");
const app = new koa();
const router = new koaRouter();
const cors = require('koa-cors');
const bodyParser = require("body-parser");

const port = 8080;

app.use(router.routes()).use(router.allowedMethods());
app.use(bodyParser.urlencoded({extended: false}));
app.use(bodyParser.json());

app.listen(port, () => {
  console.log("server koa started " + port);
});

router.get("/id/:id", async (ctx) => {
  const id = ctx.params.id;
  console.log("id was " + id);
  ctx.body = {
    "id": id
  }
});

router.get("/", async (ctx) => {
  ctx.body = {
    "message": "hello"
  }
});

当我想从我的网络服务器调用它时，我得到了这个：

Access to fetch at 'http://localhost:8080/id/azerty' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

我能做些什么来解决这个问题？ 谢谢

Answer 1

看这里Koa cors module

const Koa = require('koa');
const cors = require('@koa/cors');

const app = new Koa();
app.use(cors());

您没有在代码中使用该模块。

Answer 2

您需要 cors 模块，但尚未将 cors 添加到 app.use() 中间件。

app.use(cors())   // Add this new line 
app.use(router.routes()).use(router.allowedMethods());
app.use(bodyParser.urlencoded({extended: false}));
app.use(bodyParser.json());