Match String and add selector by native js

script.js

<script>
document.addEventListener('DOMContentLoaded', function () {
    // Get all elements with the specified class
    var targetElements = document.querySelectorAll('.berocket_better_labels_position span.b_span_text');
    // Loop through each element
    targetElements.forEach(function (targetElement) {
        // Get the number and convert it to a float
        var number = parseFloat(targetElement.textContent);
        // Check if the number is below 20%
        if (number < 20) {
            // Add a class to the parent element with the specified class
            var parentElement = targetElement.closest('.berocket_better_labels_position');
            if (parentElement) {
                parentElement.classList.add('discount-below-tweenty');
            }
        }
    });
});
</script>