I know in the question you state "I assume JavaScript is used to create this effect" but CSS can be used too, an example is below.
CSS
.fancy-link {
color: #333333;
text-decoration: none;
transition: color 0.3s linear;
-webkit-transition: color 0.3s linear;
-moz-transition: color 0.3s linear;
}
.fancy-link:hover {
color: #F44336;
}
HTML
<a class="fancy-link" href="#">My Link</a>
And here is a JSFIDDLE for the above code!
Marcel in one of the answers points out you can "transition multiple CSS properties" you can also use "all" to effect the element with all your :hover styles like below.
CSS
.fancy-link {
color: #333333;
text-decoration: none;
transition: all 0.3s linear;
-webkit-transition: all 0.3s linear;
-moz-transition: all 0.3s linear;
}
.fancy-link:hover {
color: #F44336;
padding-left: 10px;
}
HTML
<a class="fancy-link" href="#">My Link</a>
And here is a JSFIDDLE for the "all" example!