JSFiddle - React, Tailwind, and code Playground

HTML

<body>

  <div id="lefty" class="lefty">
    <!--ajax response goes here-->
  </div>
  
  <div class="righty">

      <input id="part_to_search" name="partnum" type="text" autofocus="autofocus" onchange="ajax_post()"/>

  </div>

</body>

CSS

<style>
    body{background-color: #777777;}
    #lefty{
      height: 100%;
    }
    .lefty {
        background-color: #777777;
        float: left;
        width: 85%;
        height: 100%
    }

    .righty {
      background-color: #777777;
      margin-left: 85%;
      height: 100%;
      border-left: 5px solid black;
      min-height: 950px;
    }
    #viz{
      width:100%;
      height:100%;
    }
  </style>

JavaScript

function ajax_post(){
      
      // Create our XMLHttpRequest object
      var hr = new XMLHttpRequest();
      
      // Create some variables we need to send to our PHP file
      var url = "printpuller.php";
      var fn = document.getElementById("part_to_search").value;
      var vars = "partnum="+fn;
      hr.open("POST", url, true);
      
      // Set content type header information for sending url encoded variables in the request
      hr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
      
      // Access the onreadystatechange event for the XMLHttpRequest object
      hr.onreadystatechange = function() {
        if(hr.readyState == 4 && hr.status == 200) {
          var return_data = hr.responseText;
        document.getElementById("lefty").innerHTML = return_data;
        document.getElementById("part_to_search").focus();
        }
      }
      
      // Send the data to PHP now... and wait for response to update the status div
      hr.send(vars); // Actually execute the request
      document.getElementById("lefty").innerHTML = "";

  }

function focusMe()
{
  var focusbox;
  focusbox = document.getElementById("part_to_search");
  {
    setTimeout(function() {
      focusbox.focus();
    }, 1);
  }
  
}
setInterval(function(){
 var focusbox;
 focusbox = document.getElementById("part_to_search");
 focusbox.focus();
});