title: Calling POST method by clicking a button
body: <p>this is my first time when I'm setting up the server and need help. So my goal is to set up server by NodeJS and Expresss. Let's say we have an app with Admin and Users. When Admin clicks a button, it sends some data for the server, then Users can fetch the data.</p>
  
  <p>So this is my server set up:</p>
  
  <pre><code>const express = require('express')
  const app = express()
  const port = 3000
  
  app.get('/', (req, res) =&gt; res.send('Hello World!'))
  
  app.listen(port)
  </code></pre>
  
  <p>I can add some post method, let's say:</p>
  
  <pre><code> app.post('/', (req, res) =&gt; ....);
  </code></pre>
  
  <p>So I can prepare server reaction for <code>listening</code> the POST method, but I have no idea how to send some data from my app by clicking an button (I mean <code>calling</code> this post method). I've watched a bunch of tutorials and haven't seen any real-world exercises. </p>