How do I change multiple elements with same class name using Javascript?

Question

Follow up to my previous question - I want to use a button to show / hide multiple elements with the same class name using JS, yet it appears that I can only change the firs

Answer 1

var X = document.querySelectorAll(".className");

for (var i = 0; i < X.length; i++) {

    X[i].style.cssProperty = someNumber + "unitType";

}

Example: X[i].style.width = 100 + "%";

If you want it to apply random integers:

var X = document.querySelectorAll(".className");

for (var i = 0; i < X.length; i++) {

    var rand = Math.floor(Math.random() * someNumber);

    X[i].style.cssProperty = rand + "unitType";

}