Using jquery to find values that are regular expressions in a html select

Issue

I am trying to retrieve the index of html elements in a list using Jquery 3.4+.
The common solution can be found in posts like this one or this one.

I have implemented it and it runs well until the values I am trying to retrieve are none others than regular expressions.
Here's a fiddle of what I have tried:

//let myVar = $("#myList").find(`option[text='^.*\.xlsx'])`)[0].index;
let myVar = $("#myList").find(`option:contains('^.*\.xlsx')`)[0].index;
console.log(myVar+"");

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<select size="1" id="myList"> 
     <option selected style="width:100%;">^.+\.(txt|csv|xlsx)</option>
     <option style="width:100%;">^.+\.(jpg|jpeg|png|svg|bmp)</option>
     <option style="width:100%;">^.*\.xlsx</option>
     <option style="width:100%;">^.*\.docx</option>
     <option style="width:100%;">^.*\.csv</option>
     <option style="width:100%;">^.*\.pdf</option>
</select>

I'd like to add that I can't escape characters nor change the value of what I'm looking for.
Is there a way to get it working for any value regardless of it being a standard text, a regular expression or whatever could be injected in the search function?

Solution

Still using the same strategy adopting jQuery to select the element through the :contains selector https://api.jquery.com/contains-selector/#contains1

But you need to escape the backslash \ replacing each one with \\\\

Here's a demo that is simulating the input data fetch grabbing it from a text input value:

function fetchInput(){
  return document.getElementById('input').value;    
}

function search(){
  const searchTerm = fetchInput();
  const escaped = searchTerm.replace(/\\/g, '\\\\');

  let index = $(`#myList option:contains('${escaped}')`)?.index();

  console.log(`index: ${index}`);
}

button{
  cursor: pointer;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<h1>Search</h1>
<input id="input" value="^.*\.xlsx">
<button onclick="search();">Search</button>

<hr>

<select size="1" id="myList"> 
     <option selected style="width:100%;">^.+\.(txt|csv|xlsx)</option>
     <option style="width:100%;">^.+\.(jpg|jpeg|png|svg|bmp)</option>
     <option style="width:100%;">^.*\.xlsx</option>
     <option style="width:100%;">^.*\.docx</option>
     <option style="width:100%;">^.*\.csv</option>
     <option style="width:100%;">^.*\.pdf</option>
</select>

Answered By - Diego D