如何局部刷新js函数

<script type="text/javascript">
window.onload=get;
function get()
{
document.getElementById("text_1").innerHTML="<a href='http://www.yahoo.com.cn'>雅虎</a>";
}
function inser_1(obj)
{
if(obj=="baidu")
{
document.getElementById("text_1").innerHTML="<a href='http://www.baidu.com'>百度</a>";
}
else
{
document.getElementById("text_1").innerHTML="<a href='http://www.sina.com.cn'>新浪</a>";
}
}
</script>
<div id="text_1">

</div>
<div>
<input type="button" value="baidu" onClick="inser_1(this.value);" />
<input type="button" value="xinlang" onClick="inser_1(this.value);" />
</div>