I want to display grid tree columns. I have error line 18. Thanks you sir.

Question

display tree columns grid items.
https://code.sololearn.com/WdBXYiWele7i/?ref=app

Answer 1

try this
button.addEventListener ("click",function myFunction () { var el = document.querySelector (".grid-container") ; el.style.gridTemplateColumns = "50px 50px 50px";});
On line 18