Selecting Every div inside of a class

I have something like this:

<div class=“someClass”>

<div>text</div>
<div>text</div>

</div>

I want to apply a class to every div within the someClass div

How would I do something like that?

Gain a reference to the <div class=“someClass”> element. use something like getElementsByClassName()

Then, you can find the descendant divs of that element via
myDivReference.getElementsByTagName(“div”)