koa允許跨域

const Koa = require('koa');
const app = new Koa();
const json = require('koa-json');
const cors = require('@koa/cors')
const registerRouter = require('./routes')()
app.use(json());
app.use(cors({
    origin: (ctx) => {
        if (ctx.url === '/test') {
            return "*"; // 允許來自所有域名請求
        }
        return "*"; // http://localhost:3006/
    },
    credentials: !0
}));

app.use(registerRouter)
app.listen(3004, () => {
    console.log('Koa Server Started.... listen 3004 port');
})