transition

значения свойства:

transition-property
transition-duration

css/style.css

* {
margin: 0;
padding: 0;
}
.main {
height: 600px;
width: 900px;
position: absolute;
top: 50%;
left: 50%;
margin-top: -300px;
margin-left: -450px;
}
.wrapper {
width: 33.3%;
height: 100%;
float: left;
}
#div1, #div2, #div3 {
height: 200px;
width: 200px;
float: left;
position: relative;
top: 50%;
left: 50%;
margin-top: -100px;
margin-left: -100px;
background-color: #3BA9DE;
}
#div1 {
transition: width, height, background-color, 1s;
-moz-transition: width, height, background-color, 1s;
-o-transition: width, height, background-color, 1s;
-webkit-transition: width, height, background-color, 1s;
-ms-transition: width, height, background-color, 1s;
}
#div2 {
-moz-transition: height, background-color, 1s;
-o-transition: height, background-color, 1s;
-webkit-transition: height, background-color, 1s;
}
#div1:hover {
width: 250px;
height: 250px;
background-color: #A3E61D;
}
#div2:hover {
height: 250px;
background-color: #7092BE;
}
#div3:hover {
width: 250px;
background-color: #852E76;
}

* {
 margin: 0;
 padding: 0;
}

.main {
 height: 600px;
 width: 900px;
 position: absolute;
 top: 50%;
 left: 50%;
 margin-top: -300px;
 margin-left: -450px;
}

.wrapper {
 width: 33.3%;
 height: 100%;
 float: left;
}

#div1, #div2, #div3 {
 height: 200px;
 width: 200px;
 float: left;
 position: relative;
 top: 50%;
 left: 50%;
 margin-top: -100px;
 margin-left: -100px;
 background-color: #3BA9DE;
} 

#div1 {
 transition: width, height, background-color, 1s;
 -moz-transition: width, height, background-color, 1s;
 -o-transition: width, height, background-color, 1s;
 -webkit-transition: width, height, background-color, 1s;
 -ms-transition: width, height, background-color, 1s;
}

#div2 {
 -moz-transition: height, background-color, 1s;
 -o-transition: height, background-color, 1s;
 -webkit-transition: height, background-color, 1s;
}

#div1:hover {
 width: 250px;
 height: 250px;
 background-color: #A3E61D;
}


#div2:hover {
 height: 250px;
 background-color: #7092BE;
}

#div3:hover {
 width: 250px;
 background-color: #852E76;
}

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<link href="css/style.css" rel="stylesheet" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
</head>
<body>
<div class="main">
<div class="wrapper">
<div id="div1"></div>
</div>
<div class="wrapper">
<div id="div2"></div>
</div>
<div class="wrapper">
<div id="div3"></div>
</div>
</div>
<script>
/*JavaScript*/
document.getElementById("div2").style.transition="height, background-color, 1s";
document.getElementById("div2").style.msTransition="height, background-color, 1s";
/*jQuery*/
$(document).ready(function() {
$("#div3").css({ "transition": "width, background-color, 1s" });
$("#div3").css({ "-moz-transition": "width, background-color, 1s" });
$("#div3").css({ "-o-transition": "width, background-color, 1s" });
$("#div3").css({ "-webkit-transition": "width, background-color, 1s" });
$("#div3").css({ "-ms-transition": "width, background-color, 1s" });
});
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<link href="css/style.css" rel="stylesheet" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
</head>
<body>
<div class="main">
<div class="wrapper">
<div id="div1"></div>
</div>
<div class="wrapper">
<div id="div2"></div>
</div>
<div class="wrapper">
<div id="div3"></div>
</div>
</div>
<script>
/*JavaScript*/
document.getElementById("div2").style.transition="height, background-color, 1s";
document.getElementById("div2").style.msTransition="height, background-color, 1s";
/*jQuery*/
$(document).ready(function() {
$("#div3").css({ "transition": "width, background-color, 1s" });
$("#div3").css({ "-moz-transition": "width, background-color, 1s" });
$("#div3").css({ "-o-transition": "width, background-color, 1s" });
$("#div3").css({ "-webkit-transition": "width, background-color, 1s" });
$("#div3").css({ "-ms-transition": "width, background-color, 1s" });
});
</script>
</body>
</html>