 <p>Maybe:</p> <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false"> <div class="snippet-code"> <pre class="snippet-code-js lang-js prettyprint-override"><code>alert(/^\{{2}[\w|\s]+\}{2}$/.test('{{FirstName}}'))</code></pre> </div> </div> </p> <p><code>^</code>: In the beginning.</p> <p><code>$</code>: In the end.</p> <p><code>\{{2}</code>: Character <code>{</code> 2 times.</p> <p><code>[\w|\s]+</code>: Alphabet characters or whitespace 1 or more times.</p> <p><code>\}{2}</code>: Character <code>}</code> 2 times.</p> <p><strong>UPDATE:</strong></p> <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false"> <div class="snippet-code"> <pre class="snippet-code-js lang-js prettyprint-override"><code>alert(/(^\{{2})?[\w|\s]+(\}{2})?$/.test('FirstName'))</code></pre> </div> </div> </p>