CodeMirror simple mode - regex not highlighting as expected
<p>I'm trying to use <a href="http://codemirror.net/demo/simplemode.html" rel="nofollow noreferrer">CodeMirror simple mode</a> to create my own editor and highlight some custom keywords. However, it's highlighting occurrences of these words inside other words. Here's my code to define the mode of the editor:</p>
<pre><code>    CodeMirror.defineSimpleMode(&quot;simple&quot;, {
  // The start state contains the rules that are intially used
  start: [
    // The regex matches the token, the token property contains the type
    {regex: /[&quot;'](?:[^\\]|\\.)*?(?:[&quot;']|$)/, token: &quot;string&quot;},
    {regex: /;.*/, token: &quot;comment&quot;},
    {regex: /\/\*/, token: &quot;comment&quot;, next: &quot;comment&quot;},

    {regex: /[-+\/*=&lt;&gt;!]+/, token: &quot;operator&quot;},
    {regex: /[\{\[\(]/, indent: true},
    {regex: /[\}\]\)]/, dedent: true},

    //Trying to define keywords here
    {regex: /\b(?:timer|counter|version)\b/gi, token: &quot;keyword&quot;} // gi for case insensitive
  ],
  // The multi-line comment state.
  comment: [
    {regex: /.*?\*\//, token: &quot;comment&quot;, next: &quot;start&quot;},
    {regex: /.*/, token: &quot;comment&quot;}
  ],
  meta: {
    dontIndentStates: [&quot;comment&quot;],
    lineComment: &quot;;&quot;
  }
});
</code></pre>
<p>When I type in the editor, this is what gets highlighted. I would expect the first two occurrences to be styled, but not the second two.</p>
<p><a href="https://i.stack.imgur.com/7FnqD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7FnqD.png" alt="enter image description here" /></a></p>
<p>It's obviously something incorrect with this regular expression:</p>
<pre><code>/\b(?:timer|counter|version)\b/gi
</code></pre>
<p>But I've tried it several different ways and the same pattern works correctly in other regex testers. Example:
<a href="https://regex101.com/r/lQ0lL8/33" rel="nofollow noreferrer">https://regex101.com/r/lQ0lL8/33</a> . Any advice?</p>
<h3>Edit #1:</h3>
<p>Tried this pattern in codemirror definition, dropping the /g but it still yields the same incorrect highlighting.</p>
<pre><code>{regex: /\b(?:timer|counter|version)\b/i, token: &quot;keyword&quot;}
</code></pre>