怎样用 koa 解析出 POST 请求上下文中的表单数据

index.js

const Koa = require("koa");
const app = new Koa();

function bodyParser(ctx) {
  return new Promise((resolve, reject) => {
    let postData = "";
    try {
      ctx.req.addListener("data", (data) => {
        postData += data;
      });
      ctx.req.addListener("end", () => {
        resolve(postData);
      });
    } catch (err) {
      reject(err);
    }
  });
}

app.use(async (ctx) => {
  const reqBody = await bodyParser(ctx);
  ctx.body = reqBody;
});

app.listen(3000);