JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test"></div>

JavaScript

var link = [{
  "USER_NAME": "abc",
  "USER_DOB": "10/25/1985",
}, {
  "USER_NAME": "xyz",
  "USER_DOB": "10/25/1986"
}];
var html = '';
for (var i = 0; i < link.length; i++) {
  var tableHeaders = Object.keys(link[i]);

  for (var j = 0; j < tableHeaders.length; j++) {
    var formattedStr = tableHeaders[j].replace(/_/g, ' ');
    Object.keys(link[i])[j] = formattedStr;
    html += Object.keys(link[i])[j] + ' -- ' + formattedStr + '<br /><br />';
  }
}

document.getElementById('test').innerHTML = html;