node and koa implement data mock interface

// server.js
const Koa = require('koa');
const Router = require('koa-router');
const qs = require('qs');
const assert = require('assert');

const app = new Koa();
const router = new Router();

/**
 * 获取列表数据
 * @param {request} page 页数
 * @param {request} limit 每页数据条数
 * @param {response} errno 返回状态码 0 ==> 返回成功 1 ==> 有错误
 * @param {response} hasMore 是否有更多数据
 */
let listData = require('./mock/list/list.js');

router.get('/api/getlist/:page/:limit', function (ctx, next) {
  
  const page = ctx.params.page;
  const limit = ctx.params.limit;
  const maxPage = listData.length / limit;
  
  // 构造返回对象
  let res = {
    errno: 0,
    data: {
      hasMore: true,
      data: []
    }
  };

  // 如果超过最大页面数
  if ((page*1 + 1) >= maxPage) {
    res.data.hasMore = false;
  }
  res.data.data = listData.slice(page*limit, page*limit + limit);
   ctx.body = res;
});

/**
 * 获取详情数据
 * @param {request} id 商品id
 */
const detailData = require('./mock/detail/detail.js');

router.get('/api/getdetail/:id', function (ctx, next) {

  const id = ctx.params.id
  let res = {
    errno: 0,
    data: {
      data: []
    }
  }
  res.data.data = detailData;
  // todo...
  ctx.body = res;
});

/**
 * 提交评论
 * @param {request} id 用户id
 * @param {request} uid 商品id
 * @param {request} msg 评论内容
 */
router.post('/api/comment', function (ctx, next) {
  
  const params = qs.parse(ctx.req._parsedUrl.query);
  const id = params.id;
  const uid = params.uid;
  const msg = params.msg;
  if (id === undefined || uid === undefined || msg === undefined) {
    ctx.body = {
      errno: 1,
      msg: '缺少参数'
    }
  } else {
    // todo...
    ctx.body = {
      errno: 0,
      msg: '评论成功'
    }
  }
});

app
 .use(router.routes())
 .use(router.allowedMethods());
app.listen(3000);
console.log("server is running at http://localhost:3000/");

module.exports = {
  ...

  devServer: {
    proxy: {
     // 将 `/api` 开头的 http 请求，都代理到 `localhost:3000` 上，由 koa 提供 mock 数据
     '/api': {
      target: 'http://localhost:3000',
      secure: false
     }
    }
    ...
  }
}