使用JavaScript一次更改具有相同类名的多个元素的样式？

var elements = document.getElementsByClassName("myClassName");
for (var i = 0; i< elements.length; i++) {
  elements[i].style.color = "red";
  elements[i].style.fontSize = "16px";
}

var elements = document.querySelectorAll(".myClassName");
for (var i = 0; i< elements.length; i++) {
  elements[i].style.color = "red";
  elements[i].style.fontSize = "16px";
}

Array.from(document.getElementsByClassName("myClassName")).forEach(function(element) {
  element.style.color = "red";
  element.style.fontSize = "16px";
});

Array.from(document.querySelectorAll(".myClassName")).map(function(element) {
  element.style.color = "red";
  element.style.fontSize = "16px";
});