_custom.js

(function() {  
    class ClassWatcher {
        constructor(targetNode, classToWatch, classAddedCallback, classRemovedCallback) {
            this.targetNode = targetNode
            this.classToWatch = classToWatch
            this.classAddedCallback = classAddedCallback
            this.classRemovedCallback = classRemovedCallback
            this.observer = null
            this.lastClassState = targetNode.classList.contains(this.classToWatch)

            this.init()
        }

        init() {
            this.observer = new MutationObserver(this.mutationCallback)
            this.observe()
        }

        observe() {
            this.observer.observe(this.targetNode, { attributes: true })
        }

        disconnect() {
            this.observer.disconnect()
        }

        mutationCallback = mutationsList => {
            for(let mutation of mutationsList) {
                if (mutation.type === 'attributes' && mutation.attributeName === 'class') {
                    let currentClassState = mutation.target.classList.contains(this.classToWatch)
                    if(this.lastClassState !== currentClassState) {
                        this.lastClassState = currentClassState
                        if(currentClassState) {
                            this.classAddedCallback()
                        }
                        else {
                            this.classRemovedCallback()
                        }
                    }
                }
            }
        }
    }
   	const workOnClassAddVisible = () => {
      document.getElementById("recharge-te").style.zIndex = "100001";
    }    
    const workOnClassRemovalVisible = () => {
      document.getElementById("recharge-te").style.zIndex = "10000";
    }
  	let elTeModal = document.getElementById('te-modal');
  	let classWatcher = new ClassWatcher(elTeModal, 'visible', workOnClassAddVisible, workOnClassRemovalVisible);
})();