<html>
<body>
<form>
选择一个数字:<br>
<select id="no">
<option>0</option>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
<option>6</option>
<option>7</option>
<option>8</option>
<option>9</option>
</select>
<input type="button" onclick="myFunction()" value="-->">
<input type="text" id="result" size="20">
</form>
<script>
function myFunction() {
var no = document.getElementById("no");
var option = no.options[no.selectedIndex].text;
var txt = document.getElementById("result").value;
txt = txt + option;
document.getElementById("result").value = txt;
}
</script>
</body>
</html>