router.get('/getData', async (ctx,next) => {
  // 从上下文的request对象中获取
  let request = ctx.request;
  let req_query = request.query; // 获取格式化参数
  let req_querystring = request.querystring; // 获取字符串

  // 从上下文中直接获取
  let ctx_query = ctx.query;
  let ctx_querystring = ctx.querystring;
  let obj = {
    req_query:req_query,
    req_querystring:req_querystring,
    ctx_query:ctx_query,
    ctx_querystring:ctx_querystring
  };
  ctx.response.body = {status:200,msg:'这是get测试的返回数据',data:obj};
});

var getTest = () => {
  $.ajax({
    type:'GET',
    url:'/getData"getTest()">点击测试get方法</button>

router.post('/postData',async (ctx,next) => {
  let postData = await parsePostData(ctx);
  console.log(postData);
  ctx.response.body = {status:200,msg:'这是post测试的返回数据',data: postData};
});

// 解析上下文里node原生请求的POST参数
function parsePostData( ctx ) {
  return new Promise((resolve, reject) => {
    try {
      let postdata = "";
      ctx.req.addListener('data', (data) => {
        postdata += data
      })
      ctx.req.addListener("end",function(){
        let parseData = parseQueryStr( postdata )
        resolve( parseData )
      })
    } catch ( err ) {
      reject(err)
    }
  })
}

// 将POST请求参数字符串解析成JSON
function parseQueryStr( queryStr ) {
  let queryData = {}
  let queryStrList = queryStr.split('&')
  console.log( queryStrList )
  for ( let [ index, queryStr ] of queryStrList.entries() ) {
    let itemList = queryStr.split('=')
    queryData[ itemList[0] ] = decodeURIComponent(itemList[1])
  }
  return queryData
}

var postTest = () => {
  let obj = {
    name:'啦啦啦',
    description:'我是卖报的小行家'
  };
  $.ajax({
    type:'POST',
    url:'/postData',
    dataType:'json',
    data:obj,
    success(data){
      console.log(data);
    },
    error (err){
      console.log(err);
    }
  });
}
// 添加一个post请求的按钮
<button onclick="postTest()">点击测试post方法</button>

npm i koa-bodyparser –save

// 引入模块
const bodyParser = require('koa-bodyparser');
// 挂载到app
app.use(bodyParser());

router.post('/postData',async (ctx,next) => {
  let postData = ctx.request.body;
  ctx.response.body = {status:200,msg:'这是post测试的返回数据',data: postData};
});