How do I solve this “Cannot read property 'appendChild' of null” error?

Question

I tried to use this code below, which adds buttons in slideshow on my site:

window.onload = function loadContIcons() {
    var elem = document.createElement(\"im         


        

Answer 1

The element hasn't been appended yet, therefore it is equal to null. The Id will never = 0. When you call getElementById(id), it is null since it is not a part of the dom yet unless your static id is already on the DOM. Do a call through the console to see what it returns.