function funccc(){
var c=document.getElementsByName('select1')[0]
var b=c.options[c.selectedIndex].text;
document.getElementsByName('text1')[0].value=b
}<input type="text" name="text1"/>
<select name="select1" onchange="funccc()">
<option value="1">a</option>
<option value="2">b</option>
<option value="3">c</option>
<option value="4">d</option>
</select>
var c=document.getElementsByName('select1')[0]
var b=c.options[c.selectedIndex].text;
document.getElementsByName('text1')[0].value=b
}<input type="text" name="text1"/>
<select name="select1" onchange="funccc()">
<option value="1">a</option>
<option value="2">b</option>
<option value="3">c</option>
<option value="4">d</option>
</select>
<HEAD>
<TITLE> New Document </TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!--
function getValue(str){
var newSelect=document.getElementById("select1").children;
for(var i=0;i<newSelect.length;i++){
var newOption="newSelect["+i+"]";
var aa=eval(newOption);
if(str=aa.value);
document.getElementById("text1").value=aa.innerText;
}
}
//-->
</SCRIPT>
</HEAD><BODY >
<div>
<select id="select1" onchange="getValue(this.value)">
<option value="1">1</option>
<option value="2">2</option>
</select>
<input type="text" id="text1">
</div>
</BODY>
</HTML>