▶ location.href , window.location > SCRIPT

<script type="text/javascript">

function load(){

// 1.방법

var link = document.getElementById("site").value;

window.location=link;

// 2.방법

var link = document.getElementById("site").value;

location.href=link;

// 3.방법

var link = document.getElementById("site");

window.location = link.options[link.selectedIndex].value;

}

</script>

<select id="site">

<option value="http://www.naver.com">naver</option>

<option value="http://www.daum.net">daum</option>

</select>

<button type="button" onclick="load()">click</button>