Disable Prev Control on first slide and disable Next control on last slide

Solution

You can add the css pointer-events: none to your button. That css property disable all event on an element. So something like that.

// Slick stuff
   ...
   onAfterChange: function(slide, index) {
       if(index === 4) {
           $('.slick-next').css('pointer-events', 'none')
       }
       else {
           $('.slick-next').css('pointer-events', 'all')
       }
   }

And something on the same guideline for .slick-prev element.

In that solution you should get the function out of the config and only put a reference to it with something like this.

// Inside slick config
onAfterChange: afterChange

// Below somewhere
var afterChange = function(slide, index) { //stuff here }

Also check to see if there is a way to get the length of the slider and verify it instead of hardcoding 4 in the if statement. You can probably do something like $('.slide').length

---

Edit

Here's how to implement the afterChange() function.

$(document).ready(function(){
    $('.scrollable').slick({
        dots: false,
        slidesToShow: 1,
        slidesToScroll: 3,
        swipeToSlide: true,
        swipe: true,
        arrows: true,
        infinite: false,
     });

     $('.scrollable').on('afterChange', function (event, slick, currentSlide) {
    
        if(currentSlide === 2) {
            $('.slick-next').addClass('hidden');
        }
        else {
            $('.slick-next').removeClass('hidden');
        }

        if(currentSlide === 0) {
            $('.slick-prev').addClass('hidden');
        }
        else {
            $('.slick-prev').removeClass('hidden');
        }  
    })
});

And some CSS, If you wanna do animation you should do it here.

.slick-prev.hidden,
.slick-next.hidden {
    opacity: 0;
    pointer-events:none;
}

Just use infite: false and create a custom css for class slick-disabled. Eg.

JS - jQuery

$('.my-slider').slick({
    infinite: false,
    slidesToShow: 1,
    slidesToScroll: 1
});

CSS

.slick-disabled {
    opacity: 0;
    pointer-events:none;
}

A very simple solution is:

1. set the infinite to false. eg

   $('.my-slider').slick({
    infinite: false });
   

2. add the following css

   .slick-disabled { display: none; pointer-events:none; }

and that is it.