no.js with vanilla

HTML

<div class="firstDiv">
  Hover me
</div>

<div class="target">
  my color would change
</div>
<br>

.red-color {
  color: red;
}

document.querySelector('.firstDiv').addEventListener('mouseover', function(){
	document.querySelector('.target').classList.add('red-color');
})

Ad-free

All ads in the editor and listing pages are turned completely off.
Use pre-released features

You get to try and use features (like the Palette Color Generator) months before everyone else.
Fiddle collections

Sort and categorize your Fiddles into multiple collections.
Private collections and fiddles

You can make as many Private Fiddles, and Private Collections as you wish!
Console

Debug your Fiddle with a minimal built-in JavaScript console.