Source code for https://formidable-masterminds.com/display-range-slider-as-currency/

display-range-slider-as-currency.js

/* this code is a multi-selector variation of the example found
 * in Formidable's knowledge base article:
 * https://formidableforms.com/knowledgebase/javascript-examples/#kb-format-a-slider-field-value-as-a-currency
 *
 * it uses the Intl.NumberFormat function that's built into JavaScript. No external libraries required.
 * to learn more about Intl.NumberFormat see:
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/NumberFormat
 */
 $("#field_id1 ~ .frm_range_value, #field_id2 ~ .frm_range_value").on('DOMSubtreeModified' , function() {
    var field_id = $(this)[0].previousSibling.id,
        target_elem = '#' + field_id,
        target_span = target_elem + '_display',
        formatted_html = new Intl.NumberFormat('en-US', {
            style: 'currency',
            currency: 'USD',
            maximumFractionDigits: 0,
        }).format( $(target_elem).val() );

    $(target_span)[0].innerText = formatted_html; // add the currency symbol
    var event = new Event("change");
    $(target_span)[0].dispatchEvent(event);
});

formatted-slider-html.html

<div id="frm_field_[id]_container" class="frm_form_field form-field [required_class][error_class]">
    <label for="field_[key]" id="field_[key]_label" class="frm_primary_label">[field_name]
        <span class="frm_required" aria-hidden="true">[required_label]</span>
    </label>
    [if description]<div class="frm_description" id="frm_desc_field_[key]">[description]</div>[/if description]
    [input]
    <span id="field_[key]_display" class="frm_range_value_currency">$50,000</span>
    [if error]<div class="frm_error" role="alert" id="frm_error_field_[key]">[error]</div>[/if error]
</div>

multiple-range-slider-demo.css

<style>
/* add styling for the new span */
.frm_range_value_currency {
  text-align:center;
  font-size:16px;
  display:block;
}
/* add additional sliders to the KB CSS. */
#field_demo_slider1 ~ .frm_range_value,
#field_demo_slider2 ~ .frm_range_value {
  display:none !important;
}