In bxslider i want to add a class on current slide

http://bxslider.com/options

    var slider=$('#slider1').bxSlider({
     pager: 'true',
   onBeforeSlide: function(currentSlide, totalSlides, currentSlideHtmlObject){
        $('.pager').removeClass('active-slide');   
         $(currentSlideHtmlObject).addClass('active-slide');
 //     $('#sddf').html('<p class="check">Slide index ' + currentSlide + ' of ' + totalSlides + ' total slides has completed.');
    }
});

To add class on the first visible slide you have to call onSliderLoad. Then you continue adding and removing active-slide class with onSlideAfter call.

onSlideAfter: function (currentSlideNumber, totalSlideQty, currentSlideHtmlObject) {
    $('.active-slide').removeClass('active-slide');
    $('.bxslider>li').eq(currentSlideHtmlObject + 1).addClass('active-slide')
},
onSliderLoad: function () {
    $('.bxslider>li').eq(1).addClass('active-slide')
},

https://jsfiddle.net/dariodev/587pqsct/

Here it is:

$('#slider1 ul').bxSlider({
    pager: 'true',
    onSliderLoad: function(currentIndex) {     
      $('#slider1').find('.bx-viewport').find('ul').children().eq(currentIndex + 1).addClass('active-slide');
    },
    onSlideBefore: function($slideElement){
      $('#slider1').find('.bx-viewport').find('ul').children().removeClass('active-slide');
      $slideElement.addClass('active-slide');
    }
});

JSFiddle