Saving value from document.execCommand("copy") as a string in JavaScript

Question

I have a "copy to clipboard" button that copies text generated from a search query that is going to be pasted in the url. However, when I go to paste it, the <br> tags are visible in the string. I understand how to use the .replace() function, but what I am wondering is if it is possible to save the words that are copied using the document.execCommand("copy")?

Here is my code JavaScript:

function copyToClipboard(elementId) {

    // Create a "hidden" input
    var aux = document.createElement("input");

    // Assign it the value of the specified element
    aux.setAttribute("value", document.getElementById(elementId).innerHTML);

    // Append it to the body
    document.body.appendChild(aux);

    // Highlight its content
    aux.select();

    // Copy the highlighted text
    document.execCommand("copy");

    // Remove it from the body
    document.body.removeChild(aux);

    //var query = aux.replace("<br>", "");

    console.log(aux);
    //document.body.replace(aux, queryItem);

}

And here is my HTML:

<div id="QueryStringContainer" class="QueryStringContainer">
        <div id="QueryString" class="control-label">this is a query string for users to consume</div>
        <button onclick="copyToClipboard('QueryString')">Copy to Clipboard</button>
    </div> 

Say the form generates the string The<br>cat<br>ran<br>fast, From what I have, how can I save the string as a variable using that function?

Thank you for the help!

Edit: In the console, it prints <input value="The<br>cat<br>ran<br>fast">