Why are the dropdown lists not working?

Question

css

Code: https://jsfiddle.net/jr3dccdq/ Dropdown
not working when adding

if(this.lastChild.previousSibling.style.display == 'none')

without this comparison operator, everything works, apparently thisinside ifit somehow works differently, but I don’t understand how
. What could be the problem?

Answer 1

Well of course it doesn't work. The style field is properties set via style=""HTML or .style.x = yJS. If the property is set via a CSS selector, it will be an empty string.
Corrected example: https://jsfiddle.net/Ivanq/jr3dccdq/1/