var MAX_FILTER_PRICE = 1500;

var makeDraggable = function (element, moveCallback) {

  element.addEventListener('mousedown', function (evt) {
    evt.preventDefault();

    var startPointerCoords = {
      x: evt.clientX
    };

    var startElementCoords = {
      x: element.offsetLeft
    };

    var onMouseMove = function (moveEvt) {
      moveEvt.preventDefault();
      var shift = {
        x: startPointerCoords.x - moveEvt.clientX
      };
      element.style.left = (startElementCoords.x - shift.x) + 'px';
      moveCallback && moveCallback();
    };

    var onMouseUp = function (upEvt) {
      upEvt.preventDefault();
      document.removeEventListener('mousemove', onMouseMove);
      document.removeEventListener('mouseup', onMouseUp);
    };
    document.addEventListener('mousemove', onMouseMove);
    document.addEventListener('mouseup', onMouseUp);
  });
};

var rangePriceMax = document.querySelector('.range__price--max');

function updateMaxPrice(){
  var value = getSliderValue(btnRight);
  var price = value * MAX_FILTER_PRICE;
  price = Math.round(price);
  rangePriceMax.innerText = price;
}

makeDraggable(btnRight, updateMaxPrice);

makeDraggable(btnLeft);