喜欢❤
不喜欢→_→

代码如下：

<html>
<script>
function mOver(obj) {
    obj.innerHTML = "喜欢❤"
    obj.style.backgroundColor = "red";
    obj.style.color = "#fff";
    document.getElementById("boxleft").innerHTML = "不喜欢→_→ "
    document.getElementById("boxleft").style.backgroundColor = "#fff";
    document.getElementById("boxleft").style.color = "red";
}

function mOut(obj) {
    obj.innerHTML = "不喜欢→_→ "
    obj.style.backgroundColor = "#fff";
    obj.style.color = "red";
    document.getElementById("boxleft").innerHTML = "喜欢❤";
    document.getElementById("boxleft").style.backgroundColor = "red";
    document.getElementById("boxleft").style.color = "#fff";
}

function mDown(obj) {
    obj.style.backgroundColor = "#444";
}

function mUp(obj) {
    obj.style.backgroundColor = "red";
    obj.style.color = "#fff";
    document.getElementById("mybox").innerHTML = "</br>我也喜欢你（//▽//）";
}
</script>
<style type="text/css">
#mybox {
    margin:0 auto;
    text-align: center;
    padding: 20px;
    font: bold 15px arial, "微软雅黑";
    width: 255px;
    height:50px;
}

#boxleft {
    float: left;
    padding: 20px;
    width: 87px;
    color: #fff;
    background: red;
}

#boxright {
    padding: 20px;
    color: red;
    width: 87px;
    float: right;
    background: #fff;
}
</style>

<body >
    <div id="mybox">
        <div onmousedown="mDown(this)" onmouseup="mUp(this)" id="boxleft">
            喜欢❤
        </div>
        <div onmousedown="mDown(this)" onmouseup="mUp(this)" onmouseover="mOver(this)" onmouseout="mOut(this)" id="boxright">
            不喜欢→_→ 
        </div>
    </div>
</body>

</html>