<form action="/">
 <label for="fname">First name:</label><br>
  <input type="text" id="fname" name="fname" value="John"><br>
  
  <label for="lname">Last name:</label><br>
  <input type="text" id="lname" name="lname" value="Doe"><br>
  <input type="text" hidden id="utm_source" name="utm_source">
  <input type="text" hidden id="utm_medium" name="utm_medium">
  <input type="text" hidden id="utm_campaign" name="utm_campaign">
  <input type="text" hidden id="utm_term" name="utm_term">
  <input type="text" hidden id="utm_content" name="utm_content">
  
  <input type="submit" value="Submit">
</form>
(() => {
  const getCookie = (name) => {
  const value = `; ${document.cookie}`;
  const parts = value.split(`; ${name}=`);
  if (parts.length === 2) return parts.pop().split(';').shift();
}
 
  document.getElementById("utm_source").value = getCookie("utm_source");
  document.getElementById("utm_medium").value = getCookie("utm_medium");
  document.getElementById("utm_campaign").value = getCookie("utm_campaign");
  document.getElementById("utm_term").value = getCookie("utm_term");
  document.getElementById("utm_content").value =getCookie("utm_content");
})()

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.