JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/codemirror/2.36.0/codemirror.min.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/codemirror/2.36.0/search.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/codemirror/2.36.0/searchcursor.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/codemirror/2.36.0/python.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/codemirror/2.36.0/match-highlighter.js"></script>
<link rel="stylesheet" href="http://cdnjs.cloudflare.com/ajax/libs/codemirror/2.36.0/codemirror.css">
<script src="http://cdnjs.cloudflare.com/ajax/libs/codemirror/2.36.0/overlay.min.js"></script>
<textarea id="myTextArea">print "hello world"</textarea>

CSS

.cm-highlightSearch {background: yellow;}

JavaScript

var keyword = 'hello';

CodeMirror.defineMode("highlightSearch", function(config, parserConfig) {
  var searchOverlay = {
    token: function(stream, state) {
        if (stream.match(keyword)) {
            return "highlightSearch";
        }

        while (stream.next() != null && !stream.match(keyword, false)) {}
        return null;
    }
  };
  return CodeMirror.overlayMode(CodeMirror.getMode(config, parserConfig.backdrop || "python"), searchOverlay);
});

var myTextArea = document.getElementById('myTextArea');
var myCodeMirror = CodeMirror.fromTextArea(myTextArea, {
    'mode': 'highlightSearch',
    'lineNumbers': true
});