从返回res.json的expressJS路由检索结果的方法

在Heroku免费帐户（expressJS）url上运行的我的api端点

它显示来自expressJS路由的json响应。数据如下所示

[{"_id":"5938b81bd263a5144c9d7d17","title":"mlab first entry","__v":0},
 {"_id":"5939efc7fac2b71aac4add11","title":"Second Entry","__v":0},
 {"_id":"5939efd0fac2b71aac4add12","title":"Second Entry","__v":0}]

我从localhost（）运行的代码：`

我需要格式化服务器res.json吗？还是使用res.format（对象）？

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我很感激这里的任何帮助

当我试图从Codepen访问Heroku端点时，我收到一个CORS错误。这可能就是你的应用程序没有显示任何数据的原因。您可以检查DevTools中的网络面板吗？（控制台甚至可能会显示）这是有道理的。我必须弄清楚如何在ExpressJS route中做到这一点，以便它允许所有人进行通信。我很感激。你真是太好了，花时间调查一下。祝你周末愉快。

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<link rel="import" href="../bower_components/polymer/polymer-element.html">
<link rel="import" href="shared-styles.html">
<link rel="import" href="../bower_components/polymer/polymer.html">
<link rel="import" href="../bower_components/iron-ajax/iron-ajax.html">


<dom-module id="my-view1">
  <template>

   <iron-ajax
      auto 
      url="https://shielded-caverns-24265.herokuapp.com/"
      handle-as="json"
      last-response="{{response}}">
   </iron-ajax>
 <<!--tried items={{response}} -->
 <template is="dom-repeat" items="[[response.title]]">
<div>
  <a href="{{item.title}}">   &nbsp &nbsp {{ item.title}}</a>
</div>
</template>


 <!-- this code works and pull the data from https://reqres.in/api/users?page=2
<template is="dom-repeat" items="[[response.data]]">
<div>
  <a href="{{item.first_name}} {{item.last_name}}"> {{item.first_name}}  &nbsp &nbsp {{ item.last_name}}</a>
</div>
</template>
-->


  </template>


  <script>
    class MyView1 extends Polymer.Element {
      static get is() { return 'my-view1'; }
    }

    window.customElements.define(MyView1.is, MyView1);
  </script>
</dom-module>

     router.get('/', function(req, res){
     Comment.find(function(err, comments){
        res.json(comments);
});
});