Pause video when jQuery SLICK slide changes

append-param.php

<?php
// append custom parameters to YouTube iframe to enable JS API
$custom_parameters = '&amp;rel=0&amp;enablejsapi=1';
// Append custom parameters to the src attribute of the iframe
$modified_iframe = preg_replace('/src="(.*?)"/', 'src="$1' . $custom_parameters . '"', $video_iframe);

// For Vimeo video, make sure to append ?api=1

script.js

// https://codepen.io/michaelsmyth94/pen/EVQEQV?editors=0010
//bind our event here, it gets the current slide and pauses the video before each slide changes.
$('.work-slider-for').on('beforeChange', function(event, slick, currentSlide, nextSlide){
    var currentSlide, slideType, player, command;
    //find the current slide element and decide which player API we need to use.
    currentSlide = $(slick.$slider).find(".slick-current");

    /**
     * determine which type of slide this, via a class on the slide container. 
     * This reads the second class, you could change this to get a data attribute or 
     * something similar if you don't want to use classes.
     */
    slideType = currentSlide.attr("class").split(" ")[1];

    //get the iframe inside this slide.
    player = currentSlide.find("iframe").get(0);

    if (slideType == "vimeo") {
        command = {
          "method": "pause",
          "value": "true"
        };
    } else {
        command = {
          "event": "command",
          "func": "pauseVideo"
        };
    }

    //check if the player exists.
    if (player != undefined) {
        //post our command to the iframe.
        player.contentWindow.postMessage(JSON.stringify(command), "*");
    }
});