title: Replace Topics between messages in Node-red
body: <p>I am a beginner in Node-Red and I have created the following example. Where I want to replace the data's value from "numeric" into "payload".</p>
  
  <p><a href="https://i.stack.imgur.com/BFmIY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BFmIY.png" alt="Node-red Diagram"></a></p>
  
  <p>The message from "Payload" is the following:</p>
  
  <pre><code>{
  "deviceId" : "MyAzureWebApp";
  "key" : "xxx";
  "protocol" : "mqtt",
  "data" : "{tem:25, wind:20}"
  }
  </code></pre>
  
  <p>The message from "numeric" is the following:</p>
  
  <pre><code>{
  "data":"{tem: 10, wind: 10}"
  }
  </code></pre>
  
  <p>In the function block I add:</p>
  
  <pre><code>msg.payload.replace((msg.payload.data), (msg.numeric.data));
  return msg;
  </code></pre>
  
  <p>Unfortunately, what I have done so far has not worked and I still do not understand how to solve this problem. I tried to use the change module but it only accepts one entry. So I would appreciate if someone can help me. :)</p>