Here is an example that uses jQuery to achieve your goals:
Assume you have following html:
<div>
<select id="input_count">
<option value="1">1 input</option>
<option value="2">2 inputs</option>
<option value="3">3 inputs</option>
</select>
<div>
<div id="inputs"> </div>
And this is the js code for your task:
$('#input_count').change(function() {
var selectObj = $(this);
var selectedOption = selectObj.find(":selected");
var selectedValue = selectedOption.val();
var targetDiv = $("#inputs");
targetDiv.html("");
for(var i = 0; i < selectedValue; i++) {
targetDiv.append($("<input />"));
}
});
You can simplify this code as follows:
$('#input_count').change(function() {
var selectedValue = $(this).val();
var targetDiv = $("#inputs").html("");
for(var i = 0; i < selectedValue; i++) {
targetDiv.append($("<input />"));
}
});
Here is a working fiddle example: http://jsfiddle.net/melih/VnRBm/
You can read more about jQuery: http://jquery.com/