JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>

JavaScript

$(document).ready(function() {
  console.log("api"); 

  
xhr = new XMLHttpRequest();

$(document).ready(function() {
  $.ajax({
    url: 'https://api.companieshouse.gov.uk/search?q=subway',
    type: 'GET',
    datatype: 'json',
    success: function() { alert("Success"); },
    error: function() { alert('Failed!'); },
    beforeSend: setHeader       
  });   
});

function setHeader(xhr) {

  xhr.setRequestHeader('Authorization', 'Basic bXlfYXBpX2tleTo=');
//  xhr.setRequestHeader('X-GET', 'xx');
}  

});