This code will customize range slider's value and process

range_slider_rafi.js

(function(){
let sliderValue = document.querySelector('.ff_range_value');
var number = 0;

sliderValue.insertAdjacentHTML('afterend', `<span class=range_calc style='display: block; width: 100%; text-align: center; font-size: 32px; font-weight: 600;'>$0</span>`);
document.querySelector('.range_calc').insertAdjacentHTML('afterend', "<span class='text' style='display: block; width: 100%; text-align: center; font-size: 32px; font-weight: 600;'> Potential Earnings </span>");

number = document.querySelector('.ff_range_value').innerText.split('$');
number = number[0]*15;
document.querySelector('.range_calc').innerText =`$${number}`;

document.querySelector('[data-name="rangeslider"]').onchange= function(){
number = document.querySelector('.ff_range_value').innerText.split('$');
number = number[0]*15;
document.querySelector('.range_calc').innerText =`$${number}`;
}

})();