Here's my original code:

if (document.getElementById("domain")) {
    document.getElementById("domain").innerHTML = "example.com";
}

I tried updating to this, but it's not working:

if (document.getElementsByClassName("domain")) {
    document.getElementsByClassName("domain").innerHTML = "example.com";
}

It's my understanding that it's not working because getElementsByClassName uses an array. What's the easiest way to make it update the innerHTML across all the elements with that class name? Do I have to loop through the array or is there a simpler method with pure Javascript?

EDIT: I'm making this change because I need to replace the innerHTML multiple times. Before I was just needing to replace a single element.