function _setPercentFor(targetElement, percent) {
    var self = this;
    
    //prevent overflow!
    if (percent >= 100)
      percent = 100;

    if (targetElement.hasAttribute("data-progressjs")) {
      //setTimeout for better CSS3 animation applying in some cases
      setTimeout(function() {

        //call the onprogress callback
        if (typeof self._onProgressCallback != 'undefined') {
          self._onProgressCallback.call(self, targetElement, percent);
        }

        var percentElement = _getPercentElement(targetElement);
        percentElement.style.width = parseInt(percent) + '%';

        var percentElement  = percentElement.querySelector(".progressjs-percent");
        var existingPercent = parseInt(percentElement.innerHTML.replace('%', ''));

        //start increase/decrease the percent element with animation
        (function(percentElement, existingPercent, currentPercent) {

          var increasement = true;
          if (existingPercent > currentPercent) {
            increasement = false;
          }
          
          var intervalIn = 10;
          function changePercentTimer(percentElement, existingPercent, currentPercent) {
            //calculate the distance between two percents
            var distance = Math.abs(existingPercent - currentPercent);
            if (distance < 3) {
              intervalIn = 30;
            } else if (distance < 20) {
              intervalIn = 20;
            } else {
              intervanIn = 1;
            }

            if ((existingPercent - currentPercent) != 0) {
              //set the percent
              percentElement.innerHTML = (increasement ? (++existingPercent) : (--existingPercent)) + '%';
              setTimeout(function() { changePercentTimer(percentElement, existingPercent, currentPercent); }, intervalIn);
            }
          }
          
          changePercentTimer(percentElement, existingPercent, currentPercent);
          
        })(percentElement, existingPercent, parseInt(percent));
        
      }, 50);
    }
  }
Set percent for specific element

@api private
@method _setPercentFor
@param {Object} targetElement
@param {Number} percent