I have a slideshow displaying some images. There is a function to make the current image displayed fullscreen when clicking it:

var img = document.querySelectorAll(".main-webcam-img")[slideIndex-1];

img.onclick = function () {
    modal.style.display = "block";
    modalImg.src = img.src;
}

I have prev, next buttons to scroll through the images:

function plusSlides(n) {
    showSlides(slideIndex += n);
}

and a function to see what the current slide is:

function currentSlide(n) {
    showSlides(slideIndex = n);
}

The problem: When clicking the buttons slideIndexchanges (as it should), but var img = document.querySelectorAll(".main-webcam-img")[slideIndex-1]; doesn`t update.