Change class of multiple elements

Question

I want to change class of all element which are on the right of the hovered (including) and on the left of the hovered.

HTML:

<div id="head_1" class="left_head active"></div>
<div id="head_2" class="middle_head active"></div>
<div id="head_3" class="middle_head active"></div>
<div id="head_4" class="middle_head inactive"></div>
<div id="head_5" class="middle_head inactive"></div>

This is how it looks like:

Now, when I hover over third head I want all heads on the left to change class from inactive to active, and all of them on the right from active to inactive (if they were previously active)

Answer 1

$("div").hover(
  function () {
    $(this).addClass("active");
    $(this).prevAll().addClass("active");
  }, 
  function () {
    $(this).removeClass("active");
    $(this).prevAll().removeClass("active");
  }
);

div {
    width: 20px;
    height: 20px;
    display: inline-block;
    background-color: grey;
    border: 1px solid black;
    margin: 5px;
}

.active {
    background-color: yellow;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>

Answer 2

.rating {
    float:left;
}

/* :not(:checked) is a filter, so that browsers that don’t support :checked don’t 
   follow these rules. Every browser that supports :checked also supports :not(), so
   it doesn’t make the test unnecessarily selective */
.rating:not(:checked) > input {
    position:absolute;
    top:-9999px;
    clip:rect(0,0,0,0);
}

.rating:not(:checked) > label {
    float:right;
    width:1em;
    padding:0 .1em;
    overflow:hidden;
    white-space:nowrap;
    cursor:pointer;
    font-size:200%;
    line-height:1.2;
    color:#ddd;
    text-shadow:1px 1px #bbb, 2px 2px #666, .1em .1em .2em rgba(0,0,0,.5);
}

.rating:not(:checked) > label:before {
    content: '★ ';
}

.rating > input:checked ~ label {
    color: #f70;
    text-shadow:1px 1px #c60, 2px 2px #940, .1em .1em .2em rgba(0,0,0,.5);
}

.rating:not(:checked) > label:hover,
.rating:not(:checked) > label:hover ~ label {
    color: gold;
    text-shadow:1px 1px goldenrod, 2px 2px #B57340, .1em .1em .2em rgba(0,0,0,.5);
}

.rating > input:checked + label:hover,
.rating > input:checked + label:hover ~ label,
.rating > input:checked ~ label:hover,
.rating > input:checked ~ label:hover ~ label,
.rating > label:hover ~ input:checked ~ label {
    color: #ea0;
    text-shadow:1px 1px goldenrod, 2px 2px #B57340, .1em .1em .2em rgba(0,0,0,.5);
}

.rating > label:active {
    position:relative;
    top:2px;
    left:2px;
}

<div class="rating">
    <input type="radio" id="star5" name="rating" value="5" /><label for="star5" title="Rocks!">5 stars</label>
    <input type="radio" id="star4" name="rating" value="4" /><label for="star4" title="Pretty good">4 stars</label>
    <input type="radio" id="star3" name="rating" value="3" /><label for="star3" title="Meh">3 stars</label>
    <input type="radio" id="star2" name="rating" value="2" /><label for="star2" title="Kinda bad">2 stars</label>
    <input type="radio" id="star1" name="rating" value="1" /><label for="star1" title="Sucks big time">1 star</label>
</div>