How to execute slickNext method in react-slick carousel?

I have the following React app with a Slick carousel. I created a custom Next button and need to execute the slickNext() method to proceed to the next slide. The Slick carousel docs and some of the answers for questions have mentioned the following way to call slickNext() method.

The problem is I'm getting the error slider.slick is not a function.

This is what I have tried so far

gotoNext = () => {
    var slider = document.getElementsByClassName("sliderMain")[0];
    console.log("set", slider)
    slider.slick("slickNext");
}

const SampleNextArrow = (props) => {
        const { className, style } = props;
        return (
            <div
                className={className}
                onClick={this.gotoNext}
            />
           );
        }

    const settings = {
        dots: true,
        infinite: false,
        speed: 500,
        slidesToShow: 1,
        slidesToScroll: 1,
        swipe: false,
        nextArrow: <SampleNextArrow className="customSlickNext" />,
    };

    <Slider
       id="sliderMain"
       {...settings}
       className="sliderMain"
       afterChange={this.changeSlide}
    >{ /* slider goes here */}
    </Slider>

How can I solve this?

With react-slick, you can add a ref prop on <Slider>. If you're using hooks, you can do that with useRef():

import React, { useRef } from 'react';

...

const sliderRef = useRef();

<Slider
    ref={sliderRef}
    ...
>
</Slider>

You can then use sliderRef to call Slick methods in your function:

gotoNext = () => {
    sliderRef.current.slickNext();
}

The available methods for react-slick can be found at: https://react-slick.neostack.com/docs/api/#methods