JSFiddle - React, Tailwind, and code Playground

HTML

<div class="inline-form">
<input type="email" id="email-signup" placeholder="Enter Your Email Here!"/>
<a class="nav-button" onclick="SubscribeEmail()">Notify Me</a>
</div>

JavaScript

function SubscribeEmail() {
  const emailSignupForm = document.getElementById("email-signup");
  const emailAddress = emailSignupForm.value;
  const settings = {
    method: "PUT",
    url: "https://api.sendgrid.com/v3/marketing/contacts",
    headers: {
      authorization:
        "Bearer <<MY API KEY>>",
      "content-type": "application/json",
    },
    body: {
      list_ids: ["a887ad19-2756-4101-831e-6b1a51a7cfe5"],
      contacts: [
        {
          email: emailAddress
        },
      ],
    },
  };
  
  console.log(settings);

}